you could just get one of those multi layered plastic drawers/cabinets and drill holes in the top to allow fluids to drain into the plastic drawer underneath and then it makes taking the drawer out and emptying/cleaning it really easy and you dont have to drill holes in the floor your enclosure came with.
otherwise you could use bricks, pvc, metal brackets, the list goes on. Basically anything that can support the four corners of the cage and wont rust/cause mold growth if it gets moist. Walking around Home Depot is a really easy way to find multiple solutions that fit your situation!