Cats are almost pathologically driven to sleep in the smallest space they can find. Or at least the most unique one. Place a 3x5 index card anywhere on an otherwise bare floor, and the cat will seek it out and put its butt on it.
When I was a kid we had like a colony of cats living in our garage (we couldn't keep them inside because of dad's allergies and they weren't fixed so we ended up with a lot of them) and when there were kittens my sister and I would leave the extra milk in our cereal bowls out for them. They would lick the bowls dry and then curl up in them to sleep.
My big orange one (Naruto) is drawn to baskets, boxes, laptops... Lately, I've been finding his giant butt spilling over all sides of a portable typewriter from the sixties. This is because, I think, after much trial and error, he never could get completely inside my sun hat.