A warm mug of hot chocolate with a marshmallow gently melting in the center, done in anodized aluminum rings -- smooth, cool, and lightweight. Alternating champagne and bronze small rings provide visual interest around the edge, while the ring configuration yields multiple fidgeting possibilities. I like to carefully stand mine on its edge when I'm in a long meeting.
The Fugue fidget is the largest one I make, with a diameter of 3.5" (9cm), and is composed of a total of 164 individually-placed rings (54 large and 110 small). As you can imagine, this takes a while to make, but it's really lovely to fidget with when it's done!
