Not to quash the above jig sales opportunity ..

Years ago I spent time with a well repected British Frame Builder .. No Jig . sharp files and a bench vise was most of the Shop,

Other than the brazing torch.. in the basement of an Elizabethan house.

in '75 I built a frame,(years earlier) I bought the Tube set Cut and mitered, (from a small local Eugene Builder)

and built a lugged frame my self without jigs .. torches, shop space borrowed & at Community college~