CDs being such a useful source of raw material, I cooked this up on the lathe while puttering around in the shop thinking about something else. The general idea is to align a short stack of CDs on the Sherline rotary table, close enough to the center, so that you can gnaw away on the top platter and get nearly concentric results. If you really care about concentricity, this isn’t the way to go, but …
The washer clamps the CDs in place with the bushing sticking up a bit from the top layer, so it need not be more than eyeball-aligned; the air gap eliminates the need to get the bushing height Exactly Right. If you’re perpetrating fancy machining on the CD, you probably want a form-fitting metal plate atop the stack to hold it down near the perimeter to prevent getting swarf jammed underneath. Note the stack of washers require to reduce that gaping hole to meet a 3/8-16 bolt threaded into the table.
All by itself, the bushing looks like this:
The dimensions, roughly as-built:
I used a random plastic cylinder from the scrap pile and cleaned up the edges with a razor knife. Next time, I’d put the fat end near the lathe tailstock, so as to make the chamfer easier.
Memo to Self: Use brass, dammit!