When we came back from Costco once we had this salad box kicking around that the kids were playing with - it was a good sitting spot according to Lilo.
I thought it would make a good cat bed so while I was at the fabric store I found a piece of polar fleece in the remnant bin - you could also use a dollar store polar fleece blanket.
I then found a bunch of different coloured paper that matched to decorate the box. I cut rectangles and hearts out for the girls to glue on - trying to get them to cover the writing on the box.
Then we decorated with stickers. I recently found my old stickers and had a bunch of cat ones which were perfect for this.
I then put an old pillow in the box and covered it with the piece of polar fleece.
Lilo tried to get the cat to sit in the box - he wasn't so sure. But it didn't take long before he was sleeping in it. Now over 2 months later one of the cats is almost always sleeping in the bed. It might not the be prettiest thing but the cats like it so much we can't get rid of it.