Print in Place, 15 Puzzle (sliding block puzzle) and OpenSCAD script for customization.

Print instructions

The OpenSCAD Script allows customization so you can change the puzzle font and resize the it from a 3x3 puzzle up to 10x10.
Common 15 puzzle sizes are 3x3 & 4x4.
More information about 15 puzzles, variations and how to play

Print 15_Puzzle_Print-in-place.stl (Change colors with Prusa Slicer's Add color change feature.)

Or group one of the 15_Puzzle_MMU2_Text.stl with 15_Puzzle_MMU2_Tiles.stl file for your MMU3.

Separately print 15_Puzzle_Base.stl and snap on to support the tiles, especially with larger arrays.