I saw a really nice one-piece
version of this idea (imagine a fat letter C
with three notches) at the website of some firm which bundled Rega or Moth TT's onto their turntables. And they were black, too: a big plus for many of us. I have lost the link, but if I find it...ON EDIT:
I spoke with Mr. Warren: he's never sold any to people who don't own his gear but he said he'd think it over and email me info. 1/32", 1/16" and 1/8" are the thicknesses.
One drawback of the C-shape is the less-than circular shape: maybe that's an issue??
Rega RP3, TTPSU, Groovetracer delrin, reference subplatter & counterweight, Lim double pulley
Shelter 501-II with Soundsmith Level II, Heed Quasar