Frank Krygowski, 2018-08-13 17:11+0200:
Nice. If the appearance was bothersome, you could use a black tube held
in place with black zip ties.

Black tube, yes, if I can find some, but I only ever saw white tube in
hardware stores. Black zip ties, no, bad idea, as they let the tube
slide on the sides. I would rather use some black tape.

--
Tanguy