Looking to put a mat of some sort in my stand to put the sump on since I do not have a bottom to my stand.

It will be for my 55g that I'm setting up.

Any suggestions? Perhaps Home Depot/Lowes sells something?

Note: I do not want to close in the stand with wood because the stand fits over the custom made sump. Yes....this defies "Murphy's Law" but adding a floor to the stand would defy it even more.