There is an easy way you can still make use of your old moth-eaten sweater and make your kitty happy as well. And there isn’t much work in this. The DIY way is often the cheapest and fun way to reuse and repurpose objects lying around the house. So, simply take the sweater and use some foam or other fluffy material to stuff the sleeves. Stitch shut the collar so the stuffing can’t come out through there.
Tuck the sleeves into each other, like shown in the image. Fold the extra material of the body of the sweater and stitch to the sleeves in order to make a cozy bed for your sleepy cat.