Following the TPU Video of Matthias Schwaigkofer, and because I've no space to the left and right of my printer, I've redesigned the spool holder. See the attached images.
Printing done in PET-G (dasfilament.de / Sturmgrau). The roller itself is printed in two parts so that it can be printed upright with no supports.
The author remixed this model.
I've changed the mount angle so that I can mount the spool holder behind the printer into my Ikea Ivar shelf.