I am assuming that you are trying to clamp down the litter pan in the cage and not out in your hallway or room somewhere in the house ... if so ... I have the perfect solution and it cannot be budged - not even Jaymes my huge 4.5 pound ferret can move this (he certainly tries though let me tell you!!) I have 3 of the "corner" type of litter boxes and I have punched holes near the top (one on each side) and near the bottom by the sides (one on each side) sort of like this: o o o o o o o o I am really bad with this kind of thing - anyway, take some pretty thick wire and run it through the holes and through the wires of the cage and voile! Ferret proof litter pan! (it took me a while to get this working so be patient - you have to hit all the right angles!) Good luck Marion [Posted in FML issue 2292]