Depends on how big you want to go as to how much trouble you might have with it... my pylwood tank took a while to build but I did it right...anything larger than 120 and you will need to use 2x4 bracing all the way around, you will need at least 2 gallons of marine grade epoxy and then the cost of the glass and fiberglass.. basically to build a good Diy Plywood tank 3'x2'x2' would run you around $250 in materials... any bigger and your really not saving any money over buying glass, I was confident in my work and never had a leak.. but there is always that possibility... plywood tanks these days are mostly very shallow and used for Prop tanks. If you decide to go ahead, i will be happy to give you some tips on how I build mine