Best adhesive to bind pvc to acrylic sheets?

Created bases for my cats litter boxes. One of them sometime pees over the side (seen him do it), but refuses to use an enclosed box. When his happens he will start to pee around the box because i think he gets confused. I took him to the vet and she said he was fine, so either behavioral or just a weird quirk.

The problem is that we have dark carpet and it sometime takes him doing it a couple times to notice it. So I bought acrylic panels and glued PVC barriers on the side using silicone glue, but it just didn't hold. The idea had the added benefit of catching the litter too, which was nice. However, i need an adhesive capable of binding pvc to acrylic and that won't be toxic to my cats. Any suggestions? I did some research and only end up getting more confused.