Couldn't find anything similar, so I made one myself. Comes in super useful when painting miniatures. Finally uploading it because I've gone through a few revisions, and I think I'm finally happy with it. Might need to be resized, depending on finger size. Diameter is currently around 18mm. Hope you find it useful!
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Shameless plug for my hobby youtube channel: https://www.youtube.com/@LittleGiantCrafts