Good morning, Debbie,
 
If your cage is 24" x 24" you can call or email Martin's (website:
www.martinscages.com) cages for a plastic insert/pan (which is raised
about 2" tall to prevent "accidents").  If the cage is about 24" x 18", a
hardware store, such as Home Depot, or even a "Container" store will have
plastic pans.  Or you can use those peel and stick tiles.  I would
recommed, if possible, to put down a piece of wood before sticking in the
tiles.  With the cage I had two years ago, the "gunk" tended to seep
through the cracks.  I also had a ferret (or two or seven) who were great
at pulling the tiles off the wire floor.
 
Good luck
 
Lise and Domi, Nonnie, Stacia, Dante and Cooper
[Posted in FML issue 3065]