What I finally did was similar to what David is discribing. When I'd finally made a straight strongback I snapped a chalkline down the center, I cut several form blocks, marking a perpendicular center line all the way around each. On the drill press I predrilled center holes 1-1/8" from the edge.

When I attached these to the strongback station points (framing square) I now had a line with a series of points (holes) perfectly alligned -these became Centerline Waterline+1" . Attaching the forms (cut out for plenty of play around the strong back) to these points guarenteed my forms were perpendicular to the strongback and all aligned at one point. That's when I did the projected straight edge trick. Attaching blocks on the side of the strongback I screwed each form as it was aligned. It's rock steady and checking it with any method proved it true to less than 1/16 over all. It may sink but it'll track straight all the way down.
This is based on carpentry framing, highschool geometry and surveying technique. It might be the only thing I've done well so far. Will

: I too tried fooling with the laser. It is good to make sure you dont have any
: bowing, twisting in your strongback, but not so helpful for the forms. I
: tried drilling a hole at a consistent point in each form and adjusting so
: the beam would pass through from one end to the other but the beam spreads
: to much to retain accuracy (ie you need big holes). I tried a couple of
: other methods too with no more success. I went back to string line,
: protractor and square.
: cheers
: David