As you can see in another thread posted today

Molly was spayed today. Karlin asked to see her belly cover, which we got from the vet. It covers her entire stomach from throath to behind, but it enables her to eat, and also pee and so on without problems. We also received a cone, but we should only use that if she tries to bite off her belly cover.
Molly will use this for 10 days, then her stitches will be removed.
Actually, I think it would be easy to make yourself, if your vet does not have one: A piece of cloth, six places with broad bands, two places in her behind to tie op the end, and two rings on her back to connect all bands and strings.
Have fun at the sewing machine