I have two cages for which I got the interior retrofit from Kritter Koncepts. ([log in to unmask] or www.kritterkoncepts.net ) It is made of vinyl coated 1/2x1/2 heavy woven wire, three levels with short ramps and one is a trap door so it can be shut off if needed. Got rid of the old ramps and plastic shelves, which are really for cats. The most recent retrofit I got was a bit short front to back so had to send it back so if you get one be sure to send Barry exact interior dimensions. Profits support The Ferret Nook in Wisconsin. I also have two more of the same cages that had old broken bases so I appreciate the ideas others have posted. Carol O., Tucson [Posted in FML issue 4688]