[Caddylackn]

The sheet rock metal corner is folded over the edge of the coroplast and pinched/hammered flat. Like I did on the skirts, see the skirt bottom edge. Then this metal edge is screwed to the framing. I will take another picture under the car when I get home.







I used some contact cement on the edge too, but not really needed. When the metal wrapped edge is screwed to the framing it tightly grips the coroplast and can't pull out or pull the screw head through the coroplast.

The rest of the undertray is screwed to the framing with 1/2" truss head sharp pointed screws.