A jenny wheel is a hand or mechanical mechine for flanging and creatting ball swages and the like. It is used in many fabrication workshops and training colleges. I beleave they sell them in most diy car renervation mags or engineering suppliers. hope this helps.
I would use a jenny wheel. This will turn a very good flang and keep it flat. to make it easier to turn over you could first anneal the edge. This is done by heating the edge with a flame to the correct temperature (wipe on some soap first and when it turns black it is at the right temp) leave...