Diamond, Dodecahedron, Kawai Joint

A diamond or, rather, a dodecahedron of 12 congruent triangular faces.

It is derived from the cube-based Kawai half-cube joint. Two copies make a nice-looking diamond. It can also be assembled with a half-cube for a nonahedron (9-faced polyhedron; gosh, what a name!). It makes an appealing desktop toy. I think kids may love it for its aesthetic values. It is easy to print without any support or raft. Have fun!

Update: I tried the "diamond" with a child, who immediately started spinning it between his fingers and further recommended that a stand be made so his fingers wouldn't hurt. And it turned out to be a great idea!