Following the lead of others on this site and on YouTube, I used my argon-co2 mix bottle to roll a drive shaft cover for my new floor. I taped some square tubing to a sheet of cardboard to minimize indentations from the ratchet straps I used to pull the sheet metal around the bottle. I added some pieces of 2x4 under the straps to force the sheet metal to be tight against the bottle.
I have been thinking for a long while about the top edge of the firewall. The cowl cover must be removable, so it will fasten to the top of the firewall. The top edge must be something more than just the edge of the sheet metal. Yesterday, I viewed the Homemade Tools section of Hotrodders.com. Someone had modified a pair of vise grips to roll a sheet metal edge. That inspiration was what i needed! I copied the tool using a piece of push rod and a piece of 1/2 inch square tubing cut longitudinally. I marked four parallel guide lines 1/8 inch apart along the loose top of the bed rail and started mashing the vise grip tool along the four lines. The rolled edge came out with a larger diameter than did my test pieces, but it will suffice for my need.