I've started on the ear pieces, the basic model was easier than expected but I have to add everything that stands out as separate panels if I want to be able to sand it all to a nice finishe after printing.

This is the basic model for an ear piece.

Sketch made from photo scaled to 1:1 and then given depth. Ends left and right are cut with curved sketches

Basic model with recesses for insert panels

A possible alternative to printing a solid piece would be to make it hollow.