
Hi Fillis, its the way I desingend the boxes, I make the base section slightly larger than the outside dimension of the upright sections, I drill 4 holes in the corners of the base, and put largeish nuts, fixed with bolts, so the threded end sticks up. Then fix L brackets to the sidee, to line up wiht the nuts. Place Vet bed ontop of base, cut hole to line up wiht nuts, and slide the top setion on, then use wing nuts to tighten L brackets up on to the nuts, the vet bed is held tight. It takes an extra minute or two each time you change the vet bed, but I think it is worth it. No chance of the vet bed getting scrunched up and the pups getting lost underneath.
bye
Gwen