Orchid Pennyhedron Puzzle

thingiverse

A three-piece coordinate motion puzzle that assembles into a rhombic dodecahedron was discovered by me in 2014. Unlike many 3-piece coordinate motion puzzles, the three pieces are distinct from one another. Orchids (Orchidaceae) are a family of flowering plants with orchid flowers featuring bilateral symmetry. This elegant puzzle comes together through coordinate motion and boasts 180° rotational symmetry. The term "Pennyhedron" was coined by Stewart Coffin to describe the dissection of the rhombic dodecahedron, with early versions being hollow and containing a penny inside. The final rhombic dodecahedron measures 50.3 mm in diameter and has an edge length of 30.8 mm, chosen to match the wood version and allowing for piece swapping between them. I also printed a cube version by truncating the rhombic dodecahedron, shortening the coordinate motion and resulting in a looser puzzle. However, STL files for this version are not included, but can be seen in my photos featuring red PLA. To assemble the puzzle, print two copies of the "Orchid" piece and one copy of the "Hole-In-One" (Hio) piece. The fit is critical, requiring a small enough offset to prevent looseness while still allowing assembly. The optimal offset will depend on your printer, with included pieces at offsets 20, 35, 50, and 100 microns available for selection. My printer found offset 20 too tight and offset 50 too loose, leading me to add an additional 35 micron offset that fits perfectly. Caution is advised when rescaling these pieces, as the offset will also be scaled. Resizing the puzzle smaller may result in it not assembling due to insufficient offset size.