Ornament

Start with a a degenerate convex polyhedron with two faces, both regular pentagons, one red and the other green. Starting at the center of one facet (drawn here as a white circle), in every possible direction, extend a geodesic outward in that direction until it intersects itself or hits one of the vertices (drawn as colored circles). A geodesic is a straight path that wraps around edges as though the two sides were laid flat on either side of that edge. Now unfold all the resulting geodesics into the plane as straight line segments. The resulting star-shaped region is bounded by segments of lines through the origin and arcs of circles through the origin. Print onto Shrinky Dink plastic; bake for 2½ minutes at 350° under adult supervision; let cool for 1 minute; throw at ninja hiding behind the Festivus pole.

Comments

[D. Eppstein]

I suppose you've seen another thing you can do with shrinky dinks, posted at http://tdj.livejournal.com/1520439.html ?

[Brian]

IT IS A SPECIAL SNOWFLAKE (AS AM I)