Yes i have built my own intakes and working on another. Top of the list
1) you need a welder & know how to weld or have someone else weld it for you.
2)some kinda metal Brake(this depends on how you plan on makeing any bends)
3)a mill machine? or torchs , plasma cutter
4) drill or drill press
5)and sheet metal tools snips,grinder,die grinder Etc.
Hope some of this helps. And any other Questions Welcome. }[oooooo]
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NovaMan/Twisted6/Larry