Wavy Ring

I didn't know how to find the internal diameter, so I remade the file.

The internal diameter of this one is 19 mm.

I printed it in PLA on a raft. Bed temp 60 C, Nozzle temp 200 deg C. It was difficult to remove from the raft because the design makes it flexible. Ended up with jagged edges, so needs some sanding before it's ready for wear.