I needed some dummy axles. While perusing McMaster-Carr one evening, I realized they had everything I need to make a couple of dummy axles, and then I built a rear brake bridge jig that also works for barrel-type rear rack braze-ons. Rather than create a long, drawn-out post here, I uploaded the photos to my flickr account and made complete annotations.
Homebuilt frame jigs
I hope this helps someone. If you have any questions, post them to Flickr so I can answer there. The two dummy axles and the brake bridge jig took less than two hours.
I plan on building an Arctos-style jig at some point in the future out of 8020, which I will also fully document.