I first saw these marvelous "impossible" cast puzzle creations at IPP33 in Tokyp in 2013. Absolutely amazing is what I can say...but more about those later.
The standard Cast Hook that you can buy from puzzle retailers was designed by Vesa Timonen, who also designed a number of other cast puzzles such as the ever popular (and wearable) Cast Loop and Cast Cylinder for Hanayama. It comprises two interlocking identical hooks that have been twisted at different angles and the goal is to take them apart. Its essentially a disentanglement wire style puzzle on steroids. Hanayama rates it at one star difficulty, meaning its the easiest level out of six stars and indeed it is not too difficult.
|What remains is the standard Cast Hook is on the left|
The real challenge came when I tried to assemble the Double Hook back to its original state. Despite going at it on and off over different periods for well over two days, I still cannot link all the four hooks the way it came originally. Getting three together is a cinch, what with after so much trying and practice, but the fourth hook has eluded me thus far. I cannot for the life of me remember the reverse of what I did to disassemble. From a one star difficulty quotient, I think the Double Hook has shot up to least five stars?
It makes the Cast Cake (which is an extremely challenging puzzle by all accounts) now seem rather easy by comparison. Looks like I have to contact Mr Namba for some assistance.
[Edit 7 Sept 2016: I received an email from Mr Namba with nine photos of the steps to connect everything back together. As you might imagine, even with photos, puzzles of this nature is still not easy but I managed after quite of bit of trying (with coloured tape etc) to get the Double Hook back to its original state]
If you already have a Cast Hook, buy another copy and try the assembly shown. If you don't, buy two copies and give it a go, Hanayama cast puzzles are inexpensive anyway.
To see some amazing examples of "impossible objects" using different cast puzzles, click here and scroll all the way to the bottom.