Sunday 30 September 2012

Wil Strijbos’ Exchange Puzzle

I’ve already told the story about Wil’s patter on the day of the exchange and shared all of the jokes we ended up telling about the exchange puzzle, but I pretty much avoided any discussion of the puzzle itself … so let’s address that shortcoming forthwith, he said …

Wil’s been making and selling cola (and other) bottle puzzles for quite a while now and the down-sizing move to specimen bottles makes things a little trickier for folks with normal sized hands … although I noticed that some of my puzzling mates are able to do things far quicker and easier than the rest of us given their diminutive digits. But I digress… 

Visually, this is a classic Strijbos bottle puzzle – there’s the familiar little lock dangling from a red rod inside the bottle, and the rod protrudes through the cap so it can be manipulated, a bit. In the bottom of the bottle there’s a ball bearing and at the start there’s a key dangling from a key ring attached to the top of the rod, and a key inserted into the lock in the bottle… unusually for Wil, there’s a hole in the bottom of the bottle (it’s harder to make those in the bottom of a cola bottle, although that apparently hasn't stopped him in the past!). Sadly the hole isn’t large enough to allow the ball bearing to pass through it … and your first task is to get the ball bearing out. 

There’s a fair amount you can do to begin with and it’s quite tempting to start by just unlocking the padlock inside the bottle, after all there’s helpfully already a key in there … except that’s not quite as successful as  you might like. As with all of Wil’s bottle puzzles there’s a goodly measure of times where you need to take a chance on something, not really knowing whether you will be able to undo any potential damage you might wreak … but rest assured, Wil’s designs don’t usually allow you to do anything that is totally irreversible… basically, don’t do anything stupid and you should be OK. 

There’s a fantastic little “A-Ha!” moment near the start of the solution when everything in Wil’s Exchange description finally all fits together and makes sense – which is nice because it lets you know that you’re on the right track!  Of course it’s by no means easy from there on, in fact some bits are still fiddly as heck – but they’re significantly simpler than some of those cola bottles! 

Getting the ball out and back again isn’t too tricky … but adding “my” bit – and putting the chain link around the shackle with everything back inside the bottle does require a little dexterity and chunk of patience … there are one or two little stages that can be simplified a bit with some forward planning, but even then they need a reasonably dose of dexterity to complete them… 

I know I’m biased since I was part of the crew dishing these out in the Exchange at IPP32, but I think this is a terrific little puzzle – there are effectively a series of little puzzles to solve along the way to work out how to proceed and thinking a bit ahead is generally a wise move. 

Last time I checked, Wil still had some of these available so drop him a line if you’d like one…

...and if you'd like to see what Jerry thought of it, have a look over here...

First Box update
The recent round of First Boxes that Wil produced had a steel rod inside it that was your goal … you could see it inside the box sliding back and forth and you were trying to find a way of liberating it from the box. 

In the interim Wil’s come up with a much cuter alternative: a gold anodised rod with a smiley-face on one end and a sad face on the other end. 

At the start the sad face is visible through the hole in the bottom of the box, and your goal is to find, and release, the smiley-face. 

The next round of First Boxes will all come with the new style rods, but if you happen to have one from the first round and haven’t already got a replacement rod, drop Wil a note and he’ll let you have one of the slightly cuter versions free, gratis and for nothing.


  1. Great photos! I'm struggling to get mine illuminated well! How did you take your pics?


  2. Thanks Kevin - most of them are taken in a light tent on the kitchen table with a pair of cold 500 W-ish equivalent lamps - probably overkill, but it makes them consistent - bottom pic wasn't...that was using P&S on the desk with the background removed in PS Elephants - allard

    1. What light tent do you use? And what lights? Where did you buy? I have one but the lights are rubbish and it doesn't work well at all!

    2. ...detailed email sent... :-)

  3. Hi Allard,

    I'm having trouble trouble with a final step (I think). Any chance you have a solution? Thanks.

    1. ...I've solved it, but not aware of any written-down solution for it anywhere...

    2. ...feel free to email me allard dot walker at gmail dot com or something...