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@Cosmonaut
I made my jigs myself, which are my interpretations on Tim Paterek's designs.
I made one jig for the head tube-down tube, which I also adapted to braze my track ends into the chainstays; I made a simple fixture to braze the seat tube into the BB shell, I used several V blocks and shims, I built a rear triangle fixture to hold the rear end in the right place while I brazed. Every join was done separately so as to not build any stress into the frame. I used a flat surface with V blocks and a height guage to align the front triangle, and when the frame was built I did some cold setting of the rear dropouts.
Alignment tolerances on the front triangle were as perfect as any tool I can afford can measure.
The rear end was a little difficult with those chunky track ends - they are hard to get perfect in every plane. I pulled one out and re-brazed it because I wasn't happy with the alignment. Next time I'll take more care. Everything ended up pretty much perfect, although most of the framebuilders I have spoken to agree that tiny tolerances are irrelevant in frame alignment - measurements of fractions of a millimetre are the domain of machinists and are not noticeable by human riders.