Recently I had to clamp a long project glue-up. The overall clamp length I needed was 74". I tried using long pipe clamps, but there was so much flex in the 3/4" pipe that the clamping pressure wasn’t being exerted parallel to the pipes’ axes. So, I fabricated this cheap and quick plywood aid with a few large holes for the clamp heads. It allowed me to use 24" bar clamps and keep the pressure square to the workpiece. Worked like a charm.