Finally getting back to this project. I hate painting without a booth and I can't get back to building with out painting.
I'm riveting this booth together and the idea of laying out a couple of hundred holes got me looking for a better solution. So I finally came up with an idea while inspecting some aerospace assemblies we were doing at work. Most aerospace assemblies rely on a handful of tightly toleranced (for size and location) holes to temporarily fit mating parts. When using these ATA or "Advanced Technology Assembly" holes, mating pieces are pinned while the rest of the pilot holes are drilled to size and riveted. When the other holes are done the ATA holes are finished up. In this spirit, I found this piece of angle in the scrap bin. After truing it up, I got four holes put in it with a 5" spacing a 1/2" off the inner bend. With this little tool, I only have to worry about locating one hole dead center along the edge of a panel, attach my bracket and drill the other 3 in perfect relationship. On the longer panels, I can walk my bracket to the next set of holes and repeat the process always assured of 5" spacing a 1/2" off the bend.
It's a simple little thing but will save a ton of time when it comes to banging this booth out.