The Double Eagle uses 1/8" 4130 for the landing gear/strut brackets. I cut mine using my metal-cutting band saw tipped up so I could use its little table. Even with that machine, it's a pretty slow process. By "jig saw" do you mean a hand-held "sabre saw?" You might get that to work but there are two things to keep in mind: (1) 4130 can be difficult to cut and you have to push pretty hard to make progress. (2) 4130 does not like to be cut at high speed and unless you can slow down your jig saw from the normal wood-cutting speeds, the process will devour blades at an alarming rate. If your budget can stand it, you might consider a "Porta Band" type machine along with a bench mount for it so you can concentrate on cutting and not holding up the machine. But, your idea is a good one because there are a number of metal parts that you can fabricate before making the building table.