Here's a tip, if you want your ramp to curve, take the sheet of plywood and soak it for a few days. It'll become like a wet noodle and you can shape it easier. Then when it dries, it'll be smooth, yet curved with no harsh sections. I throw it in a neighbors pool overnight (Obviously with permission).
Just build the subframe correctly, and the plywood will mold to the subframe!
L8R
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