Aha, you are teaching me how to do this. And the bag spoken of is that old habit of bag of shot for shaping and stretching metal into the right shape. The cylinders are magnets. The clamp is from eastwood for doing this sort of work. the panel repairs are all butt welds with no overlapping metal? Please, more suggestions, ideas, or techniques!!. I have a '74 that re-rusted from not being protected behind the shiny side after a restoration in 1990. So much for paying for it..., and needing floors, too. Lotsa work, but so what.
I put my cars with lotsa work to do on a spit to put the work at a comfortable height. I would suggest making one, or buying one. Especially for the work on the floors..