Pentomino puzzle STL generator
Twelve pieces, sixty squares and thousands of ways to put them together. Choose the tray, set the size and the fit, and print a pentomino puzzle with challenge cards that the generator has already solved.
Just one project? A 7-day Pro pass is €4.99, no subscription.
How it works
- 1
Choose the tray
6 × 10 is the friendly one with 2,339 solutions. 5 × 12 has 1,010 and 4 × 15 has 368. 3 × 20 has only 2, and finding either of them is a genuine achievement.
- 2
Set the size and the fit
Cell size from 10 mm to 26 mm, piece thickness from 4 mm to 10 mm, and a clearance you can tune to your printer. Letters on the pieces are optional, for anyone who wants to follow the standard names.
- 3
Add challenge cards
Up to 12 cards, each showing a few pieces already in place. The generator solves every card before it prints it, and later cards give fewer pieces away. A different card set number gives a different set of challenges.
- 4
Download and print
Tray, pieces, cards and a key card with one full solution, as STL or 3MF files. Everything prints flat without supports.
Why pentominoes
A pentomino is five squares joined edge to edge, and there are exactly twelve of them. Together they cover sixty squares, which is why the classic trays are 6 × 10, 5 × 12, 4 × 15 and 3 × 20.
They are the puzzle mathematicians and teachers keep coming back to: small enough to hold in one hand, and deep enough that counting the solutions of the 6 × 10 tray was one of the first puzzles handed to a computer, in 1960.
- 6 × 10
- 2,339 solutions. The right place to start, and the tray most people keep on the table.
- 5 × 12
- 1,010 solutions. Noticeably harder, with fewer ways out of a bad start.
- 4 × 15
- 368 solutions. Long and narrow; the awkward pieces run out of room quickly.
- 3 × 20
- Only 2 solutions. The one to leave on a friend's desk.
More packing puzzles in the same place
The pentomino tray sits among the other brain teasers in the Sets tab, and every one of them comes with cards that the solver has checked.
- Secret message
- Your message is written across the 12 pentominoes, one letter per cell, and reads only when the tray is solved the right way. Up to 60 letters.
- Block box
- Two of each of the five tetrominoes into a 5 × 8 box — the wooden block puzzle, with challenge cards.
- Soma cube
- Seven pieces make a 3 × 3 × 3 cube in 11,520 ways, with a deck of figures to build.
- Calendar puzzle
- Leave today's month and date uncovered — a new puzzle every day.
Printing the pieces
Print the pieces and the tray flat. A 0.2 mm layer height, three or four perimeters and 15–20% infill suits almost everything here, and none of it needs supports when printed flat on the bed.
The pieces are chamfered top and bottom so they slide into place without catching. A clearance of 0.3 mm suits most printers; open it up if the last piece has to be forced in.
Questions
How many solutions does the 6 × 10 pentomino have?
2,339, not counting rotations and reflections of the whole tray. 5 × 12 has 1,010, 4 × 15 has 368 and 3 × 20 has just 2.
Are the challenge cards really solvable?
Every card is solved by the generator before it is drawn, and the key card shows one complete solution. Changing the card set number gives a new set of challenges.
What cell size should I use?
The default is 18 mm, which makes a 6 × 10 tray a comfortable size for a table. Smaller cells make a travel version; much below 12 mm the pieces get fiddly to pick up.
Can children use it?
Yes, with the usual care for small parts. The challenge cards that give many pieces away are a good way in, and the letters on the pieces help when talking about them.
Related
Try it now
Pro includes this mode. Cookie cutters stay free.
Just one project? A 7-day Pro pass is €4.99, no subscription.