I just did one for my 55 gallon (actually I am in the process of staining it) and I just designed it myself. I would think about how big you want the stand to be and then just take off for your wood skin that will go on the stand (plywood) and make a 2x4 frame that matches. So if you were doing it for a standard 90 you would probably want to build your 2x4 frame the exact size of the tank, then when you put the plywood skin on you could have it go up and cover the black trim on the tank. This would also build you a little lip all the way around that would keep the tank in place.