how to correctly build a rack

Ok lets say I need to make a rack for 4 new snakes lol what size best fits adults tub wise. Any particular way that works best? Does anyone have pictures of how they set their racks up? Right now they are all just sitting in tubs stacked on each other in the reptile room so it makes it hard to get to each individual one. The room is blocked off with a heater in there so its the warmest room in the house lmao the cats even sit in there but anyways I would like them to be in my bedroom so I need to make a rack with heat before they are moved in. Anyone want to help a stressed out lady? By the way the juvies are in 16 qt tubs and adults are in 38 qt tubs are those good sizes would you say?

I built my rack by setting up my tubs ( side by side( gave me 2 per shelf) other wise just get the tub measurements ( with some extra for the top and latches) and do the math.

I used 5 sheets of plywood and 4 2x4 to cut to make framing it.

which would be better make it out of wood or pvc pipes?