beaded circle medallions

Does any one know or could point me to a tutorial on how to construct the base for those decorative medallions that are sewn onto belts etc in tribal costuming?

I can figure out the decorative parts but ... I at a loss on how to construct the base.

I tried just covering a large ring with fabric but... although it maintains it's shape it isn't really coming out the way that I want.

I wonder if I should just get out my embroidery hoop.  Make the design then sew it on to a stiffer base fabric.

suggestions welcome.

cross posted to bellydancegear.
p.s. HAPPY NEW YEAR!