For medium to large chameleon species, the easiest approach I've discovered is to place a screen cage with horizontal dimensions of 24" x 24" on top of a utility sink from Home Depot, and put a bucket under the drain of the utility sink. A 24"x24" screen cage perfectly matches the top rim of a 24"x24" plastic utility sink (about $45).
With this solution, you discard the plastic bottom of the screen cage. Set a 4' ficus tree in the bottom of the utility sink and then place the screen cage over the tree and rest it on the edges of the sink. I don't even attach the screen cage to the utility sink. I just let it rest on top. If you puts lights on top of the cage, it is heavy enough that it doesn't move.
Chameleon droppings and your plant pot are out of view down in the utility sink, and it super easy to clean.