Awesome, welcome. I have built a few quads, so I can say with confidence this should not be very hard for you. A little different maybe but pretty easy.
Why 36″x36″? I’m guessing you are mainly in it for CF sheets, is that the standard size available to you? If not smaller is better/faster/stronger/more accurate. 36′ is easy to do just a bit large. If you decide to buy the kit from here you will need extra belt. The kit comes with enough for about 24×24″. There is a calculator linked at the end of this post that might help with these sizing questions. http://www.vicious1.com/assembly/conduit-rails-tubes-pipes/