ICOSA-TRIAD was invented, patented and made by David Hutchings. Kadon started selling them in 1988. This is one of the most ingenious 3-D assembly puzzles we've ever come across. Injection-molded from molds Dave himself built, 12 wing-like pieces, three each of four bright colors, are joined into 6 pairs by frog-like tabs. It's possible to make all 6 different. These then fit together to form a "great dodecahedron," where the frogs form the six sides of an interior cube. The ultimate challenge is to assemble the ball so that all twenty triangular facets display three different colors. Many other variations of color patterns are suggested in the booklet. A very limited number of archival sets are offered as of November 2020, while they last.