depending on the printer you might need to scale the cap a bit to be rigid.

Tried printing it from PETG but that always broke.  ABS then worked nicely. PLA wans't tested yet.

For other sizes simple slicer scaling should work.

V1 Version:

Outer width is 30mm. Height is 23mm.

V2 version:

Outer width is 30mm. Height is 38mm.