My friend Fritz invited me to be part of a knitting event at his fancy geodesic dome home, so I made a hat based on the structure of his house. It ended up looking sort of like a space-age multi-colored knit helmet.

It’s not a big deal to knit up this lid. You just make a bunch of triangles and stitch them together. The only real challenge is figuring out how to make a knit equilateral triangle, but this is also not really much of a problem, and the math can be a lot of fun, too.

-description by Lisa Anne Auerbach, from the Knitty Gritty website.

Materials
Scrap yarn - use any kind, as long as it knits up in the same gauge size 6 knitting needles (or size needed to obtain gauge of 4.5 stitches per inch.

This was also on the show Knitty Gritty, episode DKNG-505