This is a Jazz Hat I designed for "My Keepon" challenge. The inner diameter is 65 mm and fits perfectly on the keepon model downloaded from shapeways.
The model has enough detail to show the difference between different fabric even in simple black plastic material. Inner surface is kept smooth to keep your keepon toy safe.
Renders are done using final JazzHat(.stl) file. (Note: Keepon toy model was used for presentation purpose only.)