Reading, lots and lots of reading.
http://www.monsterfishkeepers.com/forum ... ng.288821/
Are you skilled with woodcrafts and hand tools? If not, you're gonna wanna find somebody who is good with their hands and power tools.
The bigger you go, the more money you save versus a regular tank. Normally folks say 240g+ for plywood, but if you have spare glass laying around, any size tank is doable.
There's lots of builds out there, but the most successful layer plywood, fiberglass, and waterproofing epoxy.
I've spent the last 2 years planning and watching builds, once I get my new 180g installed I foresee a 700g pbass tank in my future.
If I cant give you an answer, I'll surely be able to find it for you and if you need help building a plywood tank, shoot me a PM, I'll be glad to lend a hand if available.
Chris