Tetro-Billes was entered in the IPP35 Puzzle Design Competition by Frederic and is classified as a 1.1 2-Dimensional assembly puzzle. In common puzzle terms, I would consider it as one from the pattern matching category of puzzles.
Now back to the puzzle. I had kept it away for about two years since 2015, forgot about it and only recently re-discovered it and decided to give it a go. The puzzle consists of five wooden pieces (made of Japanese Beech) each containing blue and yellow marbles held in holes drilled into the wood. Quality of construction is very good and the marbles all fit tightly without fear of falling loose (although Frederic indicates that they can be removed and changed about for other sorts of challenges...which I didn't try for fear of damage)
The object of the puzzle is assemble the pieces so that the marbles form five different tetromino shapes - three in blue and two in yellow, with two solutions. Sounds rather simple doesn't it? considering its just 5 pieces to move around on a flat surface. Well I couldn't be more wrong. I spent several sessions over a few days before I discovered what I thought was the solution and happily shot an email to Frederic (which I usually do when I solve his puzzles or when I need help). Or at least I thought I did. Frederic reverted to say that while I have 5 tetraminos, two of them are identical (the yellow marbles). The photo below shows a solution, but its not THE intended solution.
For anyone wanting something different to challenge your wits or if you are interested in any of Frederic's puzzles mentioned above (and mind you he may even have new ones that I am unaware of), PM me and I will link you up him. Perhaps he might just have a copy or two lying around available for sale.