When I made my paint carousels (see previous post), I wish I had known that you can get these.
It is a 3 inch 'lazy Susan' bearing, bought from Ebay for £2.99 delivered. I might still use one, or more, if I remake the carousels. I've got some ideas for making a much better one, but it will involve getting some mdf, or ply, laser cut and I've yet to get any quotes.
Meanwhile, I am going to use it with my ceramic palettes. When I am working on an individual figure, and jumping between half a dozen shades, it can be a drag (literally) to be constantly turning the palette around.