Everybody knows Dominoes. Well, Triominoes is a version of that using triangles. Invented and refined by Allan Cowan, the game became famous when it was published by Pressman Toy Corporation in 1967 as TRI-OMINOS. Each tile has three sides with numbers in the corners and to play a tile, you place it alongside another tile with matching numbers. The catch is that Triominoes don't have all possible number combinations: they just have the ones in which numbers monotonically stay the same or increase in the clockwise direction. For example, 0-1-2 is a tile, but the counterclockwise 2-1-0 isn't. Much as I like Triominoes, that aspect has always bothered me because you can easily arrange tiles in shapes that never could be completed because the missing component would be counterclockwise.

So, this is Bitriominoes (pronounced Bi-Tri-Ominoes): a bidirectional version of Triominoes. Tiles have numbers in one of three colors: green for clockwise increasing, red for counterclockwise increasing, and white for tiles that would be equivalent either way (i.e., white for any tile with two or three numbers the same). Triominoes normally wouldn't have the red ones, and having them forces people to do quite a lot more mental bookkeeping. Other than that, the game rules are unchanged from Triominoes.

The files here print an entire set as a single plate. With each tile just an inch on a side, the whole set is as portable as a deck of playing cards, but they are still easy to read and can even stand on an edge so you can play without a rack for each player.

If you can only print one color, just print trio231203.stl. If you can only do two colors, print tri231203.stl in black and the union of the other three files in white. For four-color printing, print the union of all four files, which is also what I have in the single file trio231203.3mf (for my Bambu X1 Carbon). The tiles can be printed either face up or face down. I printed them face down and took advantage of ironing to make the solid-color side of the tiles very even – you don't want your printed tiles to be easily distinguished from each other due to distinctive printing textures or defects.