Sunday 29 March 2020

Mrs S Piles on the Pressure

It's a box! But I don't collect boxes. So, therefore, it's NOT a box.
Hi guys, I hope that you are all keeping safe out there? Please please please:


You may be fit and healthy but the UK has had a healthy 21-year-old girl die of COVID-19 and continental Europe has had a 16-year-old die too. None of us are safe - the outcome depends on pre-existing comorbidities and even more importantly viral load. If you get a big dose then you may be in trouble. This explains why healthcare workers are one of the groups with a high mortality...we just get a very high exposure level despite having PPE. Even with PPE, it is very easy to lose concentration over a long shift and rub your eyes or forget to gel your hands. Staff in Accident and Emergency departments are bearing the brunt and then anaesthetic departments as well due to the fact that most Intensive care medicine (at least in Europe and Australasia) is provided by anaesthetists. Even if you don't think you are at risk - remember that you don't want to kill your or someone else's parents/grandparents!

I am not sure how much longer I will be able to keep blogging - my duties are changing day by day and as well as clinical duties, I am working on supplies/equipment and am needing to rewrite the on-call rotas as staff get moved around. I will be doing an awful lot more nights and weekend duties over the next week or so and may not be able to solve any puzzles or write about them for a while. I'll do my best to get something for you all as and when I can manage it.

During the week things got busy and my idle puzzling time dropped to zero. In the evenings, I seemed to be unable to concentrate. So Saturday was the first day off in a while and I was determined to solve something for today's blog post. I had received a delivery from Eric earlier in the week after Mrs S released a package from its' quarantine in the porch. It had the usual orange tape marking a Cubicdissection puzzle and I spend a little while wrestling a greedy cat for possession (he lurves tissue paper and loves string even more!) Inside was a box. But no, it's not a box - it can't be because I don't collect boxes. The cavity(ies) were filled with 9 beautiful wooden assemblies - I do collect wood!!!! Drool!

9 different kinds of wood and a display case
The usual sig plus beautiful workmanship on the box
I knew that I had to have this just because of the woods and the workmanship. Plus I have become more and more addicted to interlocking puzzles. This particular puzzle - yes, it is effectively just ONE puzzle was designed by Lee Sallows (I am ashamed to say that I have never seen that name before) and fabulously made by Eric from Black Limba, Walnut, Mahogany, Leopardwood, Wenge, Spalted Tamarind, Canarywood, Quilted Maple, Paduak, Red Grandis (Box). The Blurb (which I didn't read said:
Reticulated Cubes is a fascinating exploration of 3x3 cube puzzles with a novel twist. Each box contains nine pieces, and there are eight possible cube solutions. The goal is to organize the pieces in the box such that any three pieces in a straight line will assemble into a cube (tic-tac-toe style). The solution is quite difficult to find!
So, it's a kind of Sudoku and multiple interlocking puzzles! Fab!

First of all, have a closer look at the pieces and the box:

Even the grid is gorgeous!
Which wood is your favourite?
I initially set to just random cube assembly and realised that individually they were not that hard to make (no rotations or multiple moves to get them interlocked) but then when I tried to make 2 at the same time, it got harder quite quickly and then a third was really tough! I tried again and only could make one! None of the remaining pieces could be assembled! OMG! Time to Think© (that was painful). I got out a piece of paper and a pencil and did some adding up...several times! I ended up with a plan - my plan is hidden behind a spoiler button - don't click it if you ever plan on solving this yourself.

After I had done my initial planning, I set to at the breakfast table with Mrs S reading the newspaper next to me. She was a little bemused at the number of pieces and the rapid onset of muttering that occurred next to her. After an hour the muttering had escalated to swearing and she was starting to get annoyed. She asked me what I was trying to do and then asked whether I had a quieter puzzle to play with. When I told her that I HAD to solve this for the blog the following day she gave me an ultimatum...You have GOT to do this within another 2 hours or you MUST move onto something else! Aaargh! As if the pressure of work and blogging weren't enough already - she's a mean vindictive woman with a powerful right hook so I took this all very seriously.

After another 10 minutes, I actually had a second epiphany - the initial pattern that I had thought of could be narrowed down by looking at further restrictions in the pieces that can interact together at all. This was made quite a bit tougher by the fact that I seemed to be incapable of interlocking 2 pieces that really HAD to go together. Then...Aha! I had a breakthrough and some more pieces were placed in the grid and finally, just as I came up towards my deadline, I had it solved. Phew - such pressure from both puzzle and Mrs S!

The solution is behind another spoiler button - again don't click it unless you really want to see the solution.

Wow! What an incredible puzzle - the design is fabulous - I loved having to think about multiple assemblies that went side by side and am delighted with Eric's workmanship and choice of gorgeous wood. My addiction is well served here - even Mrs S liked the look of it even if she did not like my swearing.

Luckily I was able to solve it before she a) murdered me or b) physically took it off me and put another puzzle in my hands! Next up, my puzzle fro this evening is how to write a rota that usually has 30 people on it providing 3 tiers of cover with only 18 people, some of whom may disappear at any moment (but I don't know who will be disappearing)!  Wish me luck.

Stay safe everyone - really pay attention to what is being advised. It is dangerous out there to you and to your families. If you obey the advice then this may be under control within a month or so (ignore the "Orange idiot's" plan for Easter) and we can hopefully not swamp the health services beyond their ability to cope.

Sunday 22 March 2020

Brass is Good For Puzzles As Well As Viruses

Hyperboloid Burr from Big Steve and Ali
I really have had no time at all to solve anything this week - as you can imagine, work is rather crazy these days. I have spent my working week and my evenings trying to ensure that as people either go off sick or self-isolate that we have a fully manned on-call service and due to my rôle with the supplies and equipment groups, I have been trying to work out what we are going to need and ensure that we have it in the right place. It's at times like these that I am grateful for having a really good team of people behind me. Everyone thinks about the doctors and nurses in a hospital but don't forget that running any hospital is an army of people in the background making sure that everything runs and is where it should be. I could not do my job without them! Unfortunately, one thing that I could not just magic up was another 70 or 80 ICU ventilators and I guess that before long we will be using anaesthetic machines for it which is really not ideal. If you or your family don't want to be on one of those ventilators then you need to do what your governments are telling you...


Do not socialise, do not make unnecessary trips, keep apart from each other! Only go out if you are a key worker in health, key infrastructure or work in the food supply industry.

If you are young then you will probably (although not definitely) have a mild illness but how would you feel if you killed your parents or your grandparents. The elderly or chronically ill will not do well with this virus. People are dying out there!

In this day and age of self-isolation and trying to keep oneself and one's property scrupulously clean I heard (from Big Steve so it MUST be true) that apparently the Coronavirus does not survive on brass (or copper) for more than about 15 minutes! Therefore you should all put down your porous wooden puzzles which can harbour nasties for hours or days and lay your hands on some lovely solid metal!

Now, my last blog post which mentioned the TwoBrassMonkeys mentioned Scott's Shaft and Nuts and whilst it's more of a puzzling object than a puzzle itself, it is certainly a gorgeous piece of brass which may help irradicate the virus from your hands. Now I am certainly NOT advocating that you insert Scott's shaft and nuts in any orifices as that might end up with a visit to the emergency room and you really want to avoid that just now! Plus, of course, it is very angular and has sharp edges which would be very uncomfortable. Instead, you may prefer to play with another puzzle produced by the boys, the Hyperboloid Burr. It's not terribly difficult but it is beautifully made and has two lovely challenges to it.

I had first played with a very nice wooden version of this puzzle from Allard's collection many years ago at an MPP. This was Naoki Takashima’s Exchange puzzle at an IPP. Allard teel the story that it was presented as an interesting burr assembly with six identical pieces, each shaped with hyperboloid curves. Once the initial assembly had been thought about (we all know about 6 interlocking sticks) then Naoki added an additional identical piece to the pile of pieces so that a new 7 piece construction could be made. This was exactly how it was shown to me at the MPP and I loved the idea. You all know that the 6 piece assembly looks like this:

A 6 piece burr shape
The 6 piece assembly in brass fits together only by a perfect alignment of the pieces and then with a rather satisfying click. You then have something rather fetching to hold in your hands and "remove your viruses" (I'm kidding!)

The 7 piece assembly in wood took me a little while all those years ago but was a very satisfying puzzle to solve leaving a nice grin on your face.

I never found a copy of the wooden for my own collection and was delighted to see an early version of the boy's brass creation at an MPP last year and then got a copy myself in February. Of course, it's not a new challenge for me but it is still very satisfying to assemble - the precision is unbelievable - the tolerances are to the nearest 0.03mm - any tighter and it cannot be assembled and any looser and it falls apart. Again a lovely click as it snicks together.

Don't click on the button until after you have solved it yourself.

You owe it to yourself to buy something genuinely virus free and to support the 2 crazy men making us brass toys! Now I need to find some time to solve something else in time for next weekend.

Have a lovely day and stay safe! Oh yes... even if the Hyperboloid burr has no sharp edges, I DO NOT advocate internal use of the puzzle! Not even a nostril!

Sunday 15 March 2020

Packed With Thought...Which Was a Problem For Me

Wishing Well
First of all, in view of the goings-on around the world and with my current profession, I have to advise everyone out there who reads my drivel that they need to change their behaviour now. Not later, not sometime soon! NOW! Right NOW! The COVID-19 pandemic is going to affect almost everyone around you. If it continues to progress as it has then it is likely that 60-80% of the world's population will be infected and with a 15% rate of serious illness (hospitalisation) and 1-3% mortality (depending on the population involved) then this is a huge amount of morbidity and the bodies will build up. Italy's mortuaries are full and overflowing and not just with the elderly, infirm and frail...this virus is catching the young as well - only children are relatively unscathed. Yes, if you are fit and healthy then the odds are in your favour but if you had a 1 in 200 chance of being killed crossing the road (the odds for someone 40-49 years old) then you would avoid that road! If you caught COVID-19 and remained well then great for you but how would you feel if you gave it to your elderly parents/grandparents and killed them? The best thing you can do is practice social distancing as much as you possibly can. Yes, you may need to work, you need to buy food and that is fine (wash your hands etc) but don't go to bars and clubs and gyms and spread what you have about - be careful out there! As an anaesthetist in the UK, I am intensive care trained and I fully expect to have my duties change over the next week or 2 to be more of an intensivist than an anaesthetist - I really don't want to be looking down and intubating an elderly relative of someone who could have avoided this terrible illness by just avoiding social contact. I am not being alarmist - read the accounts from Italy - the affected areas have one of the best health care systems in the world and they are overwhelmed. Awful decisions are having to be made (the elderly are being allowed to die in favour of the young) and anything which can prevent a healthcare system from being overrun cannot be a bad thing.

If you stay at home, then puzzling is a very good way to pass the time - stay safe everybody!

After I posted last week showing off the whole set of upcoming puzzles from Jakub and Jaroslav's Pelikan puzzles store, Alexander Magyarics contacted me to tell me that he was pleased that I had received a copy of his puzzles and was looking forward to hearing my thoughts on them. I had started with the Osanori puzzles because Jakub was waiting for me to write a review before they could be put up for sale and Alexander had written something himself for the item page. At the end of last week, I had taken the pieces out of their storage/transport positions, taken my photos and had a very quick idle play to reveal the scale of the problem. I had suspected that these were going to be a significant challenge and I was not wrong. I tell Mrs S that I am never wrong and my struggle with these just goes to contribute yet more evidence how right I am. Unfortunately it usually only achieves a large bruise from a Whack! Ouch! The pieces that went with these packing puzzles were pretty simple:

3 simple pieces
3 more simple pieces
There are just 3 pieces to be fitted inside a 3x3x3 space in both the Pincers and Wishing well puzzles and this looks to be pretty simple at first glance...there is a lot of space and the end result will have plenty of gaps. BUT the difficulty of these puzzles is HUGELY increased by the constraint of the entryway into the frame. For the Pincers puzzle, there are 83 ways to fit the three pieces inside a 3x3x3 cube and to add to the confusion each of those 83 ways can be rotated into 1 of 6 orientations (i.e. 498 possible cubes - OMG!) and with the Wishing well puzzle, there are 50 possible cubes with a gap in the centre of the top face for the cubie on the bucket arm of the well. To do this by trial and error would be a massive task well beyond my meagre attention span.

I set to playing with Pincers first because the slot entry intrigued me. I quickly realised that the entry through that slot reduced the potential orientations of all the pieces to a tiny fraction of those possible. I formed a mental image in my mind how I could try to find a solution and set to making shapes outside the box. There were quite a few but every time I tried to insert the pieces, I realised that the "fingers" of those pincers that cover the top form a massive restriction in what is possible. Pieces can only be lifted up when the top part is under the central slot and also not trapped under the other 2 pieces. There was much effing and blinding and Mrs S began to get irritated with me - I put it down and watched some TV before another bruise or burn occurred. The only way to solve this is to make cube shapes outside of the box and to attempt to simulate the moves required for their removal. I worked on the Pincers for several hours over a 4 day period before having a huge lucky break. The sequence required is pretty complex with the pieces quite intertwined in the box and really needing a lovely sequence to unwind them from each other. What a relief when I found it! The solved state is hidden behind a spoiler button - it doesn't give that much away but I would suggest not looking until after you have tried and given up.

After my success with Pincers and with great trepidation I moved on to Wishing well. The entry of the pieces into this puzzle looks much more open and potentially from both front and back of the puzzle. The arm of the wishing well is quite mobile due to the slots on either side for it to slide through but the single cubie that hangs down from the arm is a major pain in the A! It really limits the ability to insert the pieces into the box and then seriously gets in the way of movements once inside. The final solved position is supposed to have that cubie in the centre of the top face of the 3x3x3 cube. I did find one solution with the arm of the well pushed off to one side and was actually quite pleased with myself (consider this a secondary solution to try and find). But...that was not the correct solution and I had to continue to work on it. Several days passed and I was thinking that it might be time to resort to Burrtools. The limitation on the orientation of the pieces to allow entry into the puzzle is again your friend during the exploration of this puzzle. I realised that one particular piece had to be positioned in one of 2 ways with mirror placements on the other side. Having worked this out, there are further restrictions on the other pieces. Interestingly I found that solving from the assembled state outside of the box and establishing whether I would be able to remove the pieces was not a helpful approach with this puzzle. That was a big surprise to me and I had to approach this one as an assembly puzzle with huge restrictions. It was great fun and took me 3 evenings of toil but less swearing thankfully. Last night, after work, I just managed to solve it in the nick of time for a blog post today - cutting things very fine here at PuzzleMad HQ!

Again, the photo doesn't really give away that much but only press it when you are really in need. I entered this puzzle into Burrtools (I consider that part of the fun of all my interlocking puzzles) and it revealed that the disassembly solution was a nice level 7.6.8 which is quite something for such simple pieces.

Both of these puzzles have been absolutely beautifully brought to life by Jakub and Jaroslav - the workmanship is stunning (especially in Wishing Well which includes lovely dowel work to reinforce the top elements. These will be going on sale very soon on the Pelikan puzzles website and come highly recommended by me!

These will keep you nicely occupied whilst you stay quietly at home keeping your distance from others around you.

Please please be careful out there. In my career, I have seen a lot of death and illness but not on the scale that I think is about to hit many places and has already hit parts of Europe and China. I consider many of you to be good friends even if we have never or barely met in person and it would be very sad to lose you - especially when it might be avoidable. I would also not want to see you cause illness or deaths in your own family. As much as you can, keep your distance and practice basic hygiene! Here's hoping that my own viral load is kept to a minimum by the equipment I have recently been provided with! Gulp!

Sunday 8 March 2020

Packed with Difficulty

Upcoming beauties from Jakub and Jaroslav's Pelikan Puzzles
In a very short time, Jakub will be updating the Pelikan puzzles site to allow you to buy another bunch of very interesting and fun puzzles. As usual, I was given the opportunity to get them a little early to review them prior to their going on sale. This time we have 3 new beauties from the incredible Osanori Yamamoto (yes I know I have 2 copies of one of them) and a couple from Alexander Magyarics, a relative newcomer who seems to have some very interesting designs published. Jakub sold me these with the request that I try and solve the Osanori puzzles first because those are the ones he needs a blurb for on the store...the pressure is on! These puzzles always look relatively easy but are a significant challenge which I sometimes struggle to complete in a reasonable timeline. These arrived just over a week ago and I set to under pressure straight away.

Triangle Ring 3
Here it is in Mahogany & Wenge (L) and Mahogany & Maple (R)
Osanori is incredibly prolific with 256 designs on Puzzlewillbeplayed. He has an unbelievable mind - many of his puzzles follow a particular theme and look similar but all are very different in solution and challenge level. I never get bored with these puzzles! They are also absolutely brilliant to give to non-puzzlers due to the fact that they look so deceptively simple but show both newbie and experienced puzzler that a simple-looking shape and idea can indeed be VERY difficult.

I started with the Triangle Ring 3 because it looked like it might be the easiest of them with so much space to play with:

There are 2 gigantic holes to manipulate the pieces through
Jakub has now automatically been assembling the pieces in the frames in a very nice tight arrangement and I got a rather progressive surprise that it took significant work to remove all of them. I had not realised until that moment that there were so many pieces and so little free space inside - maybe this was not going to be quite so easy? When I had all the pieces out, it is my usual first task to assemble the cube shape (or cuboid in some of the earlier puzzles) outside the frame and see how many options there might be. I was only able to assemble 2 different cubes (and have subsequently confirmed with Burrtools that this is all there is) so then set to trying to put one of them inside the frame.

If you count the cubies, you will see that there are 26 and hence only one spare cubie to allow movement of the pieces in the frame - is this going to be really tough? There appears to be a really obvious logical way to go about this - start with an assembly outside the frame and perform a sequence that will disassemble it using the restrictions the frame provides. This is rather tricky with an exceptionally affectionate cat on my lap who kept rubbing his chops on the pieces and ruining my orientation. Once he had settled down to sleep I realised that the solution to this is a beautiful and extremely logical progression. It is going to require a little bit of thought and not my usual random movements. I managed the assembly in about an hour and felt very pleased with my puzzling prowess afterwards (maybe I should have learned from my previous experiences?) The level is for the disassembly so not terribly difficult but requiring lots of thought. This was my favourite of the bunch.

A brilliant and logical solution
Flushed with success I moved on to the Triple 3 puzzle which looked alarmingly like some of the previous Osanori puzzles that I had played with. This one had been made from Cherry and Jatoba.

Triple 3
Removing the pieces showed that they were pretty simple and there would be quite a bit of manipulation room inside to play with:

Triple 3 - note that very unusual central piece
As usual, try and make a cube shape - oh boy there are quite a lot of them (11 in fact!) but this is reduced by the need to have a 2x2 cube at one corner and a filled-in cubie at the diagonally opposite one - my subsequent Burrtools use reveals that there are 8 assemblies that fulfil this requirement but at the time it felt like more. It became obvious very soon that this puzzle would need a completely different approach to the first. Attempted assembly outside the frame was not the way to go (for me, at least) and I would need to work on a combined approach - look for positions of certain pieces that would fill the holes in the frame and then try and insert the other piece(s) around that. The single cubie hole in the bottom would be there for a reason and that was what showed me the solution in the end.

Solved it! Brilliant! It took me 3 days!
There were several hours of swearing under my breath over several evenings of toil and included a comment to Mrs S that I might not solve this one before Covid-19 got me! Be systematic is my advice for this one. Again, it is really quite logical but still very hard to find the correct assembly (which is level 10.2.5). My shout of success dislodged the sleeping cat off my lap and nearly ended up with a scratch where I really didn't want one! Time for the final one:

I had left Pavillion to last because I had thought that it might be a bit of light relief from the struggle of Triple 3 - the way it was packed for delivery seemed to show that there was loads and loads of space inside and this might make the solution relatively straightforward - Lord! How stupid am I? I never seem to learn! Removing the 3 pieces showed that there really wasn't much to them:

Only 16 cubies to fit in the 27 cubie space - easy peasy? OMG no!
There are quite a few ways that these pieces can fit together into a 3x3x3 cube and thinking of that was not terribly helpful at first (there are 247 3x3x3 cubes!). OK - try limiting the assemblies to those that would close the windows in the frame - oh dear, there are an awful lot of those too (40 in fact) Having found a few nice assemblies, I realised that the shape of one of the pieces severely restricted the way it could be inserted into the frame and the precision of the manufacture meant that rotations were not possible (at least in any useful direction). Having decreased the possible assemblies by quite a bit with one single piece, I tried adding the other large piece to fill the holes in the frame and again found some severe restrictions in what was possible. BUT my brain was beginning to hurt - I was struggling to remember what I had done before and dismissed. My big Aha! moment came when I played with just 2 pieces alone and realised something very interesting. What if I did...hmmm!

OMG! I really struggled with this one
This puzzle seemed to have several phases to the solution. First work outside the frame, then restrict the orientation and then restrict it further whilst thinking of how pieces can get placed into the frame and then finally work back inside the frame to establish the exact sequence. Some rotations are physically possible and you will need nimble fingers to stop them from happening and ruining your positioning - once inside it is quite hard to see what is going on and you need to work with your mind's eye. This one took me 5 days - it is a bit of a beast (with a disassembly level of 11.7.3) despite looking so simple! It may have been that it was just my very simple brain that impaired me - I look forward to hearing whether you also struggled.

Also coming are 2 puzzles from Alexander Magyarics - I have not yet had time to solve these but they look very interesting:

Insert these 3 pieces into the frame through a T shaped slot
Just removing the pieces from the delivered puzzle shows that this is going to be a huge challenge. My copy is made from Cherry and Ovangkol and looks lovely. I suspect this might take me a little while!

Wishing Well
Quite a mobile restriction to entry
The Wishing well is stunning! Made from Mahogany, Maple and Wenge, the aim is to place all three pieces inside the wishing well so that the only one cubie sticks up outside the well itself. I am actually struggling to see how I could even construct this in Burrtools - this one might just end up never assembled!

Sunday 1 March 2020

More Brass Beauty

B-Lock II
After last week's fabulous luck with a lock, I decided to move to the other chunk of brass in my collection that has been awaiting an attempt. As I have said before, I am rubbish at solving puzzle locks despite having several Popplocks, all of Shane's Haleslocks and a couple of other of the Feldman family locks. I had absolutely loved the first lock in my collection, the amazing (essential purchase) Danlock which is available now from Dan's son Boaz Feldman and at the Paris IPP had been completely stupefied by the workmanship that had gone into the design and manufacture of the B-Lock version I (also available from Boaz). Thus, when the B-Lock II was released, I absolutely had to contact Boaz to ask about getting a copy for my own collection and to be able to write about. He put me on a waiting list and in November had completed a bunch and sold one to me. I duly admired it (especially the very nice laser inscription on the front and matching cloth bag), dutifully tried to open it as normal with the key (failing, of course!) and then tucked it away until I had some time to properly play.

The lock sat next to the Titan lock (discussed last week) and was looked at intermittently every month or so in the hope that something like an idea would spring out at me. The funny thing is that the same thing was tried every time and each time I got nowhere. Remembering the very nice trick in version 1 I had a REALLY close look at the lock but, of course, Boaz would never do the same trick twice.

Having been triumphant with the Titan, I set this as my target for the following week and took it to work. On Tuesday, after a very nice successful Abdominal Aortic Aneurysm repair, I had a little time in the coffee room for a break and the lock came out, much to the amusement of a few nurses, ODPs and consultant colleagues who were also there.

The puzzle is a standard Israeli Nabob padlock and I could see no helpful signs of tampering apart from places where access to the locking pins had been drilled and then refilled. Apart from this and some wiggle/play of the shackle, it looked like a normal lock. The fact that the pins have been drilled always makes me wonder whether unusual things can be done with the key and I tried a "thing" or two. Nope - that didn't work but it did provide a teeny tiny Aha! moment. That's interesting even if it didn't unlock it. What if I do this? AHA! again.

Gotcha! That's really quite clever.
The onlookers were quite surprised when I managed to open this new puzzle in about 3-4 minutes and several of them wanted to have a try. I kept it a few extra minutes to make sure that I really had done the opening by design rather than luck and could confirm the mechanism. I duly handed it over and several people took it in turns to solve it. Several colleagues managed it in about 10 minutes apart from one surgeon who decided it was beyond him. It was delightful to see the satisfaction on their faces when they got it.

This puzzle is available now for about £50 and, whilst expensive, is a beautifully made puzzle which clearly had a lot of work put into the manufacture. If you can manage it, I would definitely suggest you buy all 3 - they are a really good start to a puzzle lock collection.

The Monkey's Nuts
At the last Midlands Puzzle Party, I picked up a copy of The Monkey's Nuts. It's not really a puzzle apart from trying to work out how such a strange thing can happen - The normal way a nut and bolt works is "Righty-tighty - lefty-loosey". With this beautifully made and rather large (74mm x 22mm) and heavy (1lb/454g) object, turning the nuts "righty" leaves one coming off (loosening) and the other moving on (tightening) - WTF?

I had seen this made in plastic and given away at an IPP by Scott Eliott. I thought I understood how it worked and squinting at the object in the right light gives a hint (you might be able to see it in the photo above). I showed this to a few orthopaedic surgeons who tend to really appreciate fine engineering and completely failed to explain to them how it worked. A bit of Googling about found me a wonderful description of what is going on - you can download an interesting PDF showing the trick here. It really is a marvellous idea and well worth buying a copy for yourself.