Here is a nice little puzzle for those who like such things. It consists of seven pieces, one with each of the different shapes you can get by joining four hexagons edge-to-edge. The pieces can be fit together into many different compact shapes (that is, shapes with no holes in them). I chose two of them for this puzzle:
This one is called “Covynip”.
This one is “Cpoviny”.
The pictures show one way the pieces can be fit into each of the shapes, but there are others. How hard can it be to make a seven-piece puzzle? Harder than it looks, which is what makes it fun.
Why are they called Covynip and Cpoviny? The names make it easy to put the puzzle together in one of the ways that work, but only if you know how to let the name guide you to the corresponding solution. (Each solution pictured does match its name.)
I made the tetrahex pieces from PG walnut plywood and the frame from three layers of 3mm Baltic birch plywood – a frame on the top and one on the bottom with a solid layer between them. The walnut plywood is just a bit thicker than the Baltic birch, which makes it easier to remove the pieces one at a time without dumping the whole thing out.
Here are the files:
Tetrahex.zip (350.8 KB)
There’s one file for the frames and one for the pieces. The only slightly tricky thing is that since the pieces need to be decorated with score operations on both sides, you’ll need to do the usual trick of decorating and cutting the front side while ignoring the decoration operation for the back. After it’s been cut out, flip the whole design over (in this case, top to bottom), and place the pieces back into the hole from which they were cut. Then ignore the operations for the front side and set the operation for the decorations on the back to score.