The thimble (Fingerhut, foxglove) can be printed without support.

An extra ring (extra step) at the top prevents the needle from slipping.

The included model is made with FreeCAD and can be adopted.

The diameter at the entrance is 15 mm.

The inner, top surface is of 75° while it can be printed without support.

Printed on a Prusa-Mini+ in (Prusament-) PETG with 30% infill, with 5 perimeters and 0,15 mm layer height.

Brim was used but is maybe optional.

With the above settings printing takes 16 min on a Prusa Mini+.