No supports needed for this guitar pick holder. Refer to images.

I printed at 200c, 1mm retraction with a BIQU H2 hotend. TPU tends to want very little retraction. Speed was about 25mm/s, with 60% speed on the outline. 3 walls, 5 top/bottom layers. You won't need more than 10-25% infill.

If anyone wants a more custom size for the pick holding portion, let me know in the comments. I have the original files from Rhino.