I would like to build a door that I can easily take his water bowl out without moving around his whole cage and everything. Any ideas?

I'm thinking a jigsaw/dremel or something to cut a square in the side of the tub, and then screw wooden frames around the opening and then then adding hinges on one side and latches on the other.

Does anyone have any better ideas or know of a cheaper tool I can use to easily cut a square into the side of a tub?

Thanks!!!