I've used these to keep a circular shape on mugs during the initial drying, when slipcasting. They should work fine for turned items as well. They can be printed very fast on the lowest resolution.
Oh, and I'm well aware that the mug in the picture is already bisque-fired. You are supposed to exercise your imagination here, and think of a pre-leather item.
Seriously, just print them at the fastest settings. Mine are atrociously bad, quality-wise, but they work just fine anyway.
OpenSCAD, source included.