beginning a 400 build.

so im new to this whole plywood tank thing and i am needing some help with the planing. Ive read a tun of peoples threads and decided i want at least a 400 gal tank. this will be built and kept in my basement that is not finished. My whole thing is i have a very tight budget im looking to stretch this construction over the year. so first thing first i need help with the structure of the tank and what materials to use. ive decided to use 3/4 plywood but there are a tun of different types of plywood what is the right type to use. also i may want to make it bigger i haven't decided what the best size would be. i have an opening in my basement thats around 10' x5' that im i was going to use for this fish tank i was thinking doing a 6'x3'x3'.

as a side note im planning on moving my uaru into it and some severums to free up some tank space. right now i have 2-110s 2-90s 2-55s 1-40 1-20 1-10 running all full of fish actually some are over full.