Help me design my enclosure please

[Norm66]

I'm planning a 3 level enclosure (two 4'x2'x1 1/2' and one 4'x2'x1') to house my jungle carpet python, my future snake (thinking maybe a Brazilian Rainbow Boa) and my wife's ball python (is 4'x2'x1' too big for a male BP to feel secure?).

It will stand about 6' or maybe 6'-6" tall depending on how big I make the cabinet below. I imagine 3/4" plywood will be the way to go so it doesn't sag anywhere though I'll ask my cabinet making friend for sure. I'll also put casters on it because it seems like a great idea to be able to slide it around to sweep etc.

I'm thinking of going with radiant heat panels for heat and making relatively naturalistic looking enclosures since they'll be in my living room.

I've got a couple questions about the design.

First, where and how large of vents do I need? It'll have to look good on the outside as well as be secure on the inside so I'm not sure how to go about it. Could I simply drill some smaller holes in a nice neat pattern? How big and how many?

Next, what are the pros & cons of different materials and different colors for the insides of snake enclosures? Obviously water proof is a necessity so I was thinking either painting and sealing with caulk & some sort of reptile friendly polyurethane or similar but I also thought about the stuff they make kitchen backsplashes out of. Is color just personal preference? Cleanliness? White might be easier to spot dirt but black would hide it better?

And lastly, for now, what about doors? Two doors vs. one? Open down vs. out? Sliding vs. hinged? Glass vs. Plexi/Lexan/Acrylic? What works best for you? I don't have kids and rarely have kids visit so locks aren't necessary but they would obviously have to be secure.

I'm sure I'll have some more questions as I progress but I've still got a while before I'm ready to begin construction.

Thanks.