with enough support you can really use any water resistant material that makes contact with the top of tubs.
ive seen people use clear vinyl meant for auto windows (like jeeps) and a wooden frame with good results. if you want to make the frame and shelves entirely out of 3/8 pvc i agree OhhWatALoser, it depends on the size of the tubs. if the tubs are too big and heavy you could get some sagging. smaller tubs would give more support to the shelf above.
what ever you decide to do let us know and put up some pics of the build. i'd love to see how it works out.
good luck!
"you only regret the risks in life you DON'T take."
I havent gotten em yet. But I found a sign shop that will sell it to me. I dont know for sure they have 3/8 but they said they have 1/2 for 100 a sheet. Im just wonderin if it will work since it would be cheaper
1.1 Het Albino Ball 1.0 Spider
1.0 Mojave Ball 0.1 Pinstripe
0.1 Honey Bee 0.2 Normal
1.0 Caramel 0.1 Mojave het Caramel
Just remember that unless you're routing/gluing it together, the thinner the material the smaller target area you'll have when putting screws in the shelves.