Hey man, on the one thread, you asked how to make the curve of a ramp. When I need to make a ramp curve, I tak a piece of string, and anker the end to some thing like a tree, then measure out for the radius I want(usually 10 foot for 3 foot high ramp or smaller, and 12 foot for bigger). where you measure to, tie a pencil(carpenders pencil works best). Then lay the plywood so that the pencil just reaches the two poins(starting bottom, and lip top), ant race from one to the other, keeping the string taunt. This works like a giant compass, and keeps the curve consistent(no eccellerations or surprises in the feel of it). After doing this, cut the first one, then lay it no top, and trace it for the other so you know they'll be exactly the same.

I used this method to build this set: http://www.pinkbike.com/photo/781149/
Hope this helps you.