Well, the tool I made for forming the beads worked well (see Starting on the firewall) but when I welded up the holes drilled for the clamp, the whole panel warped like a pretzel. I tried hammering the panel out but it looked bloody awful. Here is a picture of the completed panel. It is hard to see the wrinkles with all the black paint, but if you look carefully enough you can see it.
So, after a nice hot cup of tea to contemplate the error of my ways, I realized the solution cannot involve drilling holes through the sheet metal that need to be filled later. Kind of obvious -eh?
So I built a completely new tool consisting of a base made of three 2×4’s topped with a piece of MDF with a u-shaped groove routed in it. This is topped by two more 2×4’s to clamp the steel sheet in place. I also made a new forming tool to shape the steel into the u-channel. Here is the new tool with the MDF exposed so you can see the channel.
And here is a piece of scrap sheet metal being worked on.
And finally, here is the end result.