Cage cage bottoms

Normally, no. If the cage is on a table or floor then you don't need any on the bottom unless you want them there.

If you build a cage stand out of grid panels, then there is typically a top surface of grids (top surface of the cage stand I mean, but the same grids serve as the bottom surface of the cage), and then the coroplast rests on top of that. But as PiggiePaws said, you don't need grids if you have a firm supporting surface for the coroplast, like a table or the floor.

Thanks all!

I think I might build one with some type of stand or storage underneath!
I'll have to look into it!