Ady you don't bend the flat piece, just cut out the approx shape, rest the rolled piece on it and solder, file/linish the external corner then run round with teh odd leg calliper to mark teh width of the flat leg and file.
Not sure how easy it would be to roll a ring from 3/4" square brass if you did it Julians way unless you had substantial rollers, I've done it with 5/16" and that was tricky enough.

Edited By JasonB on 15/02/2016 13:24:11