That's a great fix for a rusted out window channel. I really
like the idea of using SS but the core mandrel and forming dies
for the SS would have to be a tighter fit and a harder material
than the 1/2" alum channel that you used.
I made this bender up in order to bend the cats whisker ends
uniformly without destroying them. At the time the pre-bent
ones weren't available. I think dies would be relatively easy
to make if one had access to a small bench lathe. The varying
channel radius could be made easily by step bending them with
this set up:
http://www.pbase.com/dennygraham/image/123536616Denny Graham
Somewhere in the frozen north of Sandwich, IL