Bondo for the bottom?

[Franquixote]

I am thinking more and more I need to cut a hole in the bottom and out in a drain. It is plywood right now.
What's the easiest way to do this? I have a 3.75" hole saw which fits a drain I bought. I was thinking of cutting the hole then using "Bondo" which is a fiberglass filler, making the edges a little higher so it would naturally drain toward the middle. Simple bucket underneath to catch the dirty water.

Anyone have a better idea?
I can't do bio-active because it is only about 2" deep before bottom of the door.

 

[absolutbill]

I don't know that you'd need the Bondo. If you cut a hole in the plywood I would think that the lack of support would naturally cause the middle to sag just enough to drain that water. Then, you could attach a PVC pipe from the hole down into a bucket to prevent spillage. Have you coated the plywood in anything to prevent it from rotting from being exposed to water?

 

[Franquixote]

It's painted
I'm just looking for some extra measure to extend the life of the enclosure and make it more sanitary.

I'm hoping someone has some experience using the stuff. Putting tile down will be an all day thing and involve a tile saw, grout, precise cuts, etc.

Anyone have a better option than Bondo?