I’ve had success with 6mil plastic sheeting from the hardware store. You can usually find it near the painting supplies. It comes in clear, opaque, and black. Usually cutting each panel size and duct taping works best. I have had trouble trying to do a three side sheet with one go.
I use a shower curtain cut to fit and attach with command strips of course making sure there is no sticky side of the command strip anywhere my Cham can get to it. Then if I want to open one side I can just unvelcro it . I can take the whole thing down and put it back up easily. The curtain is cut so that it wraps around the cage, that way there is less humidity loss.