There is another alternative - Lortone makes a centrifugal disc
finisher option for their magnetic disc finisher. There are two
bowls - one for dry and one for wet compounds. The trick on both is
to avoid getting the workpieces and media stuck between the bottom of
the bowl and the spinning disc. I have found that these work well
within limits. Your work pieces need to be small and light. Rings
need to be jigged to avoid impingment. Anything silver and heavy
doesn’t work, especially if you have fine silver bezels.