How hard would it be to build my own cab? I am looking at a couple of eminence speakers and I would like to expand my 112 to a 212 with an external cab, I figure this will work better If i want to start jamming with people and maybe even play a few small gigs.

Would it be possible to build a "scalable" cab where I could add more (2) speakers as I get the money for them? or would this be useless, Im asking because I really have no idea what the future has in store for me expect very little money for the remaining years of college. So I am trying to head off future costs as much as possible.

Any ways are there things I need to consider like shape, size and angle? I like a really tight heavey bottom end so should it be a closed back? if it is just a 212 would there be any advantage to stacking the speakers rather than placing them side by side. Kinda like half a slanted 4x12 cab?