Just made 18 stips 3" wide (about 18" long) and sewed together. Then squared it up. Then folded and cut the angles. Saw it on a TV show.
Then added the edging - hint - use the same color edging. Was really a pain putting it on.
Didn't take but about 20 minutes to piece all of the strips. I did not put any padding in between, since it was thick enough with just the two sets of strips. I think I will put some interfacing in the next one, though.