Houdini's Torture Cell ranks as one of the top puzzles amongst the mechanical-puzzle blogging group (see Oli's, Allard's, Kevin's and Neil's reviews where all have given the thumbs up!). My guess is that it is also probably the favourite of many puzzlers out there. Designed and made by Brian Young of Mr Puzzle Australia, the Houdini was Brian's exchange puzzle at IPP31 in Berlin last year. It is currently available from Mr Puzzle Australia (and I think William Strijbos has a few left as well).
The Houdini measures 10cm x 4.8cm x 4.8cm and is made of a combination of wood (not sure what type tho'), acrylic and metal. The Houdini consists of a vertical acrylic square hollow tube placed on a wooden pedestal. Inside the acrylic tube is a small ball bearing that rolls around. On the top is a round wooden peg inverted into the acrylic tube. This peg represents Houdini (who himself was actually tied and suspended upside down during his first public performance in the Torture Cell at the Circus Busch in Berlin in 1912). Quality, construction, fit and finish of my copy is overall very good (although there was a little roughness on the edges of the top and bottom wood blocks inside the acrylic tube).
The object of the puzzle is to free Houdini from his upside down position (ie to get the peg to become right side up). Everything that is needed to get the wooden peg (Houdini) right side on top of the tube is found within the puzzle itself. Within the puzzle are also a number of magnets as one would gradually discover. There is no need for external tools and certainly no force whatsoever in the form of banging, tapping, shaking the puzzle etc is necessary (and Brian states this in the accompanying puzzle leaflet). For this puzzle, you can see everything you are doing... just the kind of puzzle I like very much! From my own experience here, there are 7 steps needed to free Houdini and make the peg upright. The Houdini is a sequential puzzle in that you must go through all the necessary steps one at a time (and in the correct sequence) to finally solve the puzzle.
For me, the Houdini is a relatively easy puzzle and I was able to solve it in under 10 minutes (TIP - nothing is hidden from view.... if you examine the puzzle carefully and spend some time thinking first, you will probably be able to figure out how the puzzle is solved). Notwithstanding, I enjoyed this puzzle very much because I can see and am aware of the progress (or regress) of each step that is needed to take me to the final solution; that is getting the inverted peg from inside the acrylic tube to the top in the upright position. I got more and more excited as I got closer to the end. As a puzzle, the Houdini is rather elegant in its simplicity...yet the design approach and solution are both very unique. All that makes for a very unusual and interesting yet sufficiently challenging puzzle for most people. The Houdini in my opinion is really a breath of fresh air and differentiates itself from the normal and traditional genres of puzzles we are generally accustomed to.