# Tetra-Flop

## Designer: Dr. Volker Latussek

This puzzle measures: 90 mm x 90 mm x 50 mm

Material: Bubinga / Elm

**Dr. Volker Latussek wrote about it:**

*“This puzzle shouldn’t exist. On the one hand, TETRA FLOP is just an add-on and on the other hand it’s an impure design. It’ll become clear that it’s an add-on when Pelikan publish a small series of FLOP puzzles in due course. That series was sparked by a call from Oskar van Deventer to suggest new cages for the SOMA CUBE. Although I’d already worked on a similar idea a while ago, I gave it another go, and in fact this time turned out to be more productive than back then and I had a lot of fun playing with the new ideas and especially working with Oskar. (Thanks Oskar!) In the FLOP series there will of course be a SOMA FLOP. When FRITZ FLOP appears, I’ll explain why I called the series FLOP. The puzzles in the FLOP series contain between five and seven of the eight possible Tetra cubes. Each box has one rectangular opening and the box is completely filled by the pieces. The number of pieces adds up nicely in TETRA FLOP from all eight possible Tetra cubes, but I haven’t found a clean FLOP design. While I can’t definitively say that there isn’t one, I have only managed to find one impure design with an extra opening on the back, which might be a clue to the (unique) solution. For me, the solution contains such wonderful rotations that I decided I had to publish TETRA FLOP despite my reservations. That, and Pelikan didn’t stop me. I hope you’ll forgive my indiscretion and enjoy this very challenging puzzle in spite of the design “shortcomings” – and indeed continue to look forward to my small series of FLOP puzzles.”*

**Kevin Sadler wrote about it:**

*“Another masterpiece by Volker! This packing puzzle is gorgeous and chunky. The substantial box is Elm and the vibrant pieces are Bubinga. It consists of all eight possible Tetrominoes which need to be formed into a 4x4x2 cuboid but done through a 1½x4 voxel hole in the top. There is a small hole in the bottom which is not quite big enough to let you put fingers through to move the pieces around inside. It quickly becomes apparent that the size and position of this hole is perfect to allow rotations of the pieces in certain directions inside the box. This is obviously going to be a challenging puzzle. Having removed the pieces for my photo, I wanted to put them back in the same way so that I could carry it in my work bag for a few days. Sigh! I couldn’t even find the way to replace them in the transport position which had the 4x1x1 stick just lying on top. This might just prove impossible for me. Volker had also commented on this to me and yet again he seems to be apologising for a “less than pure” puzzle! The fact that the box needed a hole to facilitate some of the rotations to his mind makes the puzzle less worthy and again, I have to disagree. The purity of the puzzle does not in any way detract from the wonderful sequences of moves that are required to solve it! Again, this puzzle is a masterpiece and I just do not understand how his mind works to find these designs. I initially tried making the required shapes outside the box and then looking to see whether I could do so through the limited opening. Each shape I found has to be looked at in 8 different orientations. I am not very good at Soma type assemblies and having found 4 cuboids and 32 different failed attempts at inserting them into the box, I went to Burrtools to see how many possible assemblies there might be and was horrified to see that there are 695! Aargh! At this point I had asked for some help and the solution file was sent to me. I was very careful to glance through squinted eyes and only saw the positions of 3 of the pieces and used this as my starting point. Another 3 days and I had found a few assemblies that might be promising but just could not get them in the box. Back to Burrtools – I constrained the solver to have those 3 pieces in the positions that I had seen and now I had only 60 possibilities and also did not need to bother with rotation of the assembled cuboid. The fourth of the assemblies that Burrtools had found did look promising and I set to. Oh boy! There are a LOT of rotations in this and they must be done in the right order and right position. Volker is absolutely right, this has some wonderful rotations in it which are a joy to explore. This is a seriously difficult puzzle! It is not for the faint hearted and only the very best (or luckiest) of you will manage to solve this without help. If I had not been shown the position of 3 pieces then I think I would still be at it for weeks if not years. This is perfect for the puzzle geniuses or the suckers for punishment! Thank you Volker!”*