Edward, Both Metalliferous and 46th Street Jewelry Supply (both in
NYC) had a nice supply of mandrels last week when I was up there.
Both had “odd size” mandrels, as well, including (I’m pretty sure)
ones that would fit your needs – oval mandrels for shaping larger
bezels. You might try giving one or both a call or a visit if you’re
in the area.
Handcrafted and Unique Artisan Jewelry