I bought a little tray that clamps onto a table at Bed Bath & Beyond. I've used it on some of my sewing tables where the area on the right was not quite large enough to hold everything that seems to accumulate there when I'm sewing.
This one is much nicer than what I have; I'm thinking about buying it. The one I have does not swivel.
https://www.amazon.com/Stand-Steady-.../dp/B07DY1Q9RB