/\/\ that
and i usually stand the bike on it's ass, hold the aluminum up agaist the bottom of the frame with a clamp or two, then just trace the frame shape onto the sheet, i also leave extra to bend up under and bolt thru with the footpegs
and also up front...... leave long, slight bend, and bolt on under the front bumper mounts
then you'll only need a strap on each side half way back
i also glue (Goop brand) 2" pieces of rubber heater hose to the frame in a few spots to add cushioning and prevent chafing the paint on the frame, eventually ending up rusted, spacing it down with the hose also aids in drainage
edit....and don't forget to mark and drill a hole for the tranny oil drain plug