Wednesday 22 July 2020


William Hu’s been designing interesting interlocking puzzles for a good few years now – his designs have often involved twists and turns of the sort that make BurrTools less useful than normal. About a month ago Eric produced 60-odd copies of Geneva and they didn’t last long. 

Geneva is a 4*4*4 almost cube – that’s not a spoiler – you can all count the cubies and see you’re always going to be a few short! It’s made up of ONLY FOUR pieces and it is decidedly non-trivial! 

My favourite sort of assembly puzzle – just a few pieces – you can convince yourself you know where all the pieces must go – and then you cannot find a way of getting them there. 

That’s pretty much the story with this one as well – although I will admit that I had a wobble in the middle of my solve where I began to doubt whether that was the only way to put these pieces together into an almost-cube. BurrTools merrily confirmed I was being an rrrs that was the only assembly so I went back to bashing my head against the desk. 

Knowing where the pieces must end up, and knowing who designed it and that it will invariably involve some rotations REALLY DOESN’T HELP. It is still a wonderful challenge… but the final realisation of how things need to go together and the inspired bit of choreography they perform along the way is an absolute delight – there’s a wonderful reward for persevering and finding just the right combinations to encourage the pieces to intertwine properly.

This is another excellent design from young master Hu!

Friday 17 July 2020

Thanks Michel!

A little while back my mate Michel was experimenting with some little tensegrity designs and offered to make a few if people were interested… 

I was, and I don’t have the skills or the patience for bending long bits of rod into some rather precise shapes, so I sent him some PayPal and he posted me this neat little creation. 

The hexagons each have a protruding hook and four bits of chain hold up(!) the uppermost piece… but it doesn’t quite look like it should work. 

(Just think about that – a chain pushing something up…) 

Your brain tells you that the whole thing should really just collapse if it were obeying the rules of the universe… and yet it’s quite stable, and can support objects placed on the uppermost piece. (The rods are neatly notched to keep the chains in the right place too – nice job!)

I quite like having little things like this dotted around the Puzzle Cave to make visitors think a bit – everyone always works it out quite quickly, but the glint in the eye when they first see it and you can almost hear them saying to themselves “Hang on a minute…”, is priceless. 

Thanks, Michel, for giving me a little bit of impossible for the Puzzle Cave.

Sunday 12 July 2020

Nested Cubes

Back in January, before the whole world went a little weird, I acquired a copy of Tom Lensch’s Nested Cubes from Ethel. Tom had entered it in the 2012 Nob Yoshigahara Puzzle Design Competition and I played with a copy back in DC, but got pretty much nowhere in solving it, so I was delighted to find a copy looking for a new home. 

The puzzle looks pretty innocuous at first glance in its disassembled form – come to think of it, it looks pretty innocuous in its solved form as well – it’s the little bit in between those two that might lead you to a little bit of madness though!

You’re give four cubic boxes with lids, and a little cubie to sit inside the smallest of the boxes… each of which have a series of holes drilled through them… and then the largest box has a brass rod sticking up in the centre of the base… or rather it should be in the centre of the base, only it isn’t – Tom’s drilled most of the holes in the “wrong” place too… so instead of merely piling them inside one another and closing the lids, you need to find just which orientation each one needs to go inside the next one so that the brass rod can pass sufficiently far inside the stack to allow the final lid to be closed. 

Thankfully the boxes are all cubes – thus making every possible orientation possible -he said, somewhat tautologically – I mean, you wouldn’t want the number of possible assemblies reduced in any way, now would you!? Although having said that, I have found myself solving this one on a few occasions swearing blindly that I have now literally tried every single combination and they will not work!

In spite of that, some clear thought and sightlines can help you plot a path through the morass and lead you ultimately to a single closed box with the others all neatly stacked inside. 

Fiendish, Mister Lensch, fiendish!