I've been thinking about doing this so I'll look forward to that
It's really not that hard, bars are one of the simplest things to fabricate. The tough part is getting them symetrical and if you can do it without slugging/sleeving then you can do it without welding.
The process is pretty simple:
1. take a welding rod, bend it the shape of the handlebars that you want to produce
2. transfer your bend radius(s) to a wooden jig with a strip of sheetmetal on the outside surface
3. Bake a bunch of sand in the oven to remove all moisture
4. cap the ends of the tube and fill it with the water-free sand (keeps the tubing from kinking).
5. clamp it to your jig, heat it up with a torch, and bend to shape.
6. The rest is details that will depend on your application (i.e. using riser spuds vs. risers)
5. slugging for grip and controls etc..