okay but Pua has a sheet metal tray in her cage and it is very very noisy. If it's perfectly flat it might be okay but will probably get bent over time.

Jupiter was in Pua's cage before Pua finaly came to fill it. It is two dog Xpens on top of each other and with metal shelvings that I put wood on for him while he was in there. He loves getting up high. Someone else I know built one like that but build a nice frame around it. You could get extra pannels so make it just about any way you want. That would take care of the cage bars and have doors built in.