Step 8: Final fitting
At first I was worried that my cat would be unhappy wearing the costume, but as it turns out he really likes it. Like many cats, he's got a strong instinct to sit inside of things so even when I took the costume off of him he got right back in. I would worry about him injuring himself if he wore it while I wasn't directly supervising him, but he definitely seems to appreciate the concept. Also, he appears to be able to walk around freely while wearing the costume, which is adorable!
While your cat is not wearing the tetrahedron it can be placed on its side to make a quilted cat tent-nook-bed thing, which both my cats (even the one that's far too skittish to be costumed) like very much.