I cut all the cardboard triangle, taped them together, and then painted them gold or silver so that the individual icosahedron and dodecahedron would be obvious. The black around the edges of the dodecahedron is also paint to outline its shape.

You need 60 of each triangle (A and B).
You can print out the attached blueprint and use it as is or make your own; just make sure that the sides labeled "X" are the same length.