Both of these Moebius illustrations, that I had seen at the exhibition in Toulon, were done on bristol paper, 82×128 mm, using alcohol ink Brushmarkers and Promarkers.
Sepia ink with nib for the outline of the Moebius bust monolith, and warm grey markers:

Uni-ball pin pens (thin and really thin), and coloured alcohol ink markers for the blond Narcissus: