I got the arbor press at a machinery place that resells machinery. It had some kind of jig bolted to it which was great cause I didn't have to make the base plate the die is bolted to. My first attempt at the die was wrong and after a bunch of tries this is where I tired out and stopped. I went through a long trial and error to set all the gaps and curvature to make it work. It is close enough and much better than any commercial patch panels I have seen. The biggest error I have is with the angle of the flat right side of the die with respect to the bead part. I have them parallel and really the right side should angle up a couple of degrees. Also the the right side of the bead should be deeper to make a more pronounced entry into the bead. What they make for me will be fine since the whole bottom will all be the same :)
I made them using a milling machine to make a crude shape and then lots of filing. They can be made by welding parts together as I did for another die I made. When working the metal through the dies I have found the best approach is to first make a 90 bend in the edge the sheet metal as this will act as a guide to keep the bead straight. Mine does leave marks that I have to file out afterwards. I have been doing little changes in the dies with each try and the marks are getting smaller. Basically I am rounding off the edge of the upper die that is face us in the picture above.
It took me a while to make this tooling up. I did this with very limited experience and only some ideas gleaned from some shop pictures I found online of guys making custom motorcycles. They used Delrin plastic to make a fender. I also found some neat ideas for making a wire bead roller tool. That will happen later on, but at least I have a lathe now to make my own at home. I only have to learn how to use it now.