The frames of the sheetmetal roller are made of 12 mm mild steel plate which I had lying around in the “will-come-in-useful-some-day” pile. The rollers are made from EN8 steel bar at 50 mm round, as this is a harder material and should not get as easily marked by your work.  Mild steel would also work okay if the machine is going to be used only occasionally in the shed. For the frame spacers I used 16 mm round bar. You will also need a length of 12 mm threaded rod and some 16 mm square steel for the top retaining brackets.
I machined grooves in the rollers on the lathe  to allow me to roll or swage round bar (6 mm in my case). I also partially reduced the length on one end of all three rollers to create a small space if I wish to roll a thin metal piece that has a folded lip.
I chose the second version with the adjustable top roller over two bottom driving rollers because  the second option doesn’t needs a set of interlocking gears. With the second option, you can drive the rollers by a chain-and-sprocket arrangement and it doesn’t require any adjustment.

Read more in the April/May 2010 issue of The Shed