Print the 3 parts and twist them together and put the flexible filling of a Big pen in the head.
This creates a large pen of 35 * 5 cm, but the shaft can also be omitted or printed several times to make the pen even bigger.
The pen with 1 shaft has a storage space of 23 * 4 cm and without shaft a space of +/- 7 * 4 cm.
The flexible filling is guided in the pen via a shaft to the side wall, so that there are no obstacles in the middle of the storage space.
I printed everything on my Prusa Mini+ with 0.20mm layer height and 15% infill. It is wise to give the internal thread some support.
The author marked this model as their own original creation.