Looks like the 5.5 HP shop vac I picked up for the vacuu-form table might actually work. I was rather worried that it wouldn’t be powerful enough, but a test run of the vacuum today showed that it was plenty strong, even for such a large surface area. In fact, I may not have put enough supports inside the table to keep it from collapsing, as the pegboard surface bowed inwards rather significantly, even when I didn’t have a perfect seal on the drop sheet plastic I was using for my test. I think it’ll hold well enough, but it was really surprising to see how much it bowed the surface when I turned the vacuum on.
Current progress – everything is built and mounted at this point, just need to sand down some edges on the rack I use to hold the plastic for heating, and figure out a way of holding it in place while it gets heated, then I’m good to go for a first run – should happen sometime tomorrow.
I’ll post pictures as soon as it’s fully functional, along with instructions on how it was built.