Well, as a man who watches every penny, I am using marine grade plywood(coated with an extra 2 layers of epoxy) for the back, bottom, and 2 side panels. And acrylic or glass or plexiglass can be used for the front panel. This may not look as good, but its a whole lot cheaper than doing an all glass tank and also allows the fish to feel more secure by not having the transparent glass. Here are a few good websites for info on buliding these tanks: http://www.geocities.com/gletiecq/fish.html http://fp.marksfish.f9.co.uk/diy/plywood.htm http://www.athiel.com/lib6/tank.htm http://jan.boegh.net/akvarium/Fort%C3%A6llinger/118G%20Tank/118%20G%20Plywood%20Tank. htm.

Here is a pic of a pretty rough looking 140 gallon tank.