I have just become an ower of two 15" L7's and two kicker KX1200.1 amps and now I think that I want to do a wall but dont know where to even start with building a wall ie. box size, how to build it, do I make a fg backing and build out the rest, building a wall is something i have never tried yet and I think that it would be fun, keep in mind that i will be adding two more KX1200.1 amps (two per sub) but my question is the wall and how to build it

Build it with wood and screws and liquid nail. Search around, there's a couple people here with walls. Box size, check kicker for specs.