Darin you must be skilled to be able to use a pad on a deck lid and not create lows. I am diabetic and so I don't have good circulation which hurts me when trying to run my hand over and feel for highs/lows. I have to rely on straight edges and tic-tac-toe if the panel isn't a concave or hi-crown. If it is concave or crowned,etc., then as you know shaped blocks of anything similiar works. By the way, does anybody sell sanding blocs that are the same size and same shape of a F-100 pass. door?