whoa nice frame! Seems impossible to do

Regarding jigs, one thing I like about the ones I have is their relative adjustability. If you mess up a few mm in the fork length you can move the DT-HT angle or BB drop a bit while conserving your desired HT angle. So I guess it saves a bit of time. But redoing a drawing or a CAD doesn't take too long.

Another cool, minimalist and drawing-based jig is the one Alex Meade makes. And +1 on having a lathe/mill around! I don't use them often but I'm glad I have access to them.