I wanted to have as flat a wasteboard as possible. After reading about the sag in the center of the wasteboard, measured by some guy with a runout caliper chucked up in his spindle, I decided to do this mod, where you put several sheets of MDF under the wasteboard and the bolt down the whole mess. Well, I went even one step further. I made a 3" tall torsion box with 1/2" MDF, then put bolts through the whole torsion box and through the wasteboard and standoff MDF sheets. I think I ended up using 5.5" 1/2" diameter bolts in the end, then sealed the whole assembly with waterproof caulk to keep moisture from warping stuff. It’s tough to see in this picture, but those little four bolt heads are all that peaks through the top. I use carriage bolts to minimize the amount of visible metal.