Tetrahedral Spikey, Tetrahedron

thingiverse

Tetrahedral Spikey: Each side of the big triangle is about 86mm. A raft would be necessary for printing; support is not needed. Starting with an equilateral triangle, one can extrude at a tapering angle of -19.4712 degrees (arccos(1/3) -90 ) for a tetrahedron, and then continue to extrude in the same way each central triangle (1/4 of the initial triangle) on the four faces. This is a simple and meaningful design project for inviting students to explore the world of 3D design. Of course, a touch of trigonometry would be useful, too. Warning: The spikey can be dangerous for small children. Please consider flexible filament when possible. References: 1. https://en.wikipedia.org/wiki/Tetrahedron 2. http://mathworld.wolfram.com/Spikey.html