Im Diy
 

i was wondering how hard it would be to make an intake manifold, i mean i could take it to a shop and have it done, but whats the fun in that? is it as simple as welding some pipe together with peices to fit? or are there certain angles involoved?

and in case your wondering, i'm planning on changing my single downdraft carb to dual sidedrafts and it'll need a crazy custom manifold

For the money you would be better off buying a Shunk2 or Eldebrock one.

I agree with C's. You also have to fabricate a way to angle and machine the holes provided for the injectors. Go here to get ideas:
http://www.honda-tech.com/zeroforum?id=53