Roll out a long thin strip of platinum. Cut one end to a longish
Save the pieces you’ve cut off the tapered end to fuse with later.
Curve the bar in a wood or steel block. I’ve even used pitch. I like
to use a length of plain drill stock or a small ball punch laid on
it’s side. Once it’s well curved you can just hammer or burnish the
metal onto the drill stock or what ever you use for a mandrel. You’ll
want to close the gap at this point.
Roll out your scraps as thin as you can. Cut into small pallions and
use those to weld your seam shut.
Then draw through a plate to the size you want.
Have fun and make lots of jewelry.