I liked the hanging wall design, but wanted something smaller, which can be printed in one time on my MK3S. So I designed this model around those mirrors : https://fr.aliexpress.com/item/33038861135.html (S size).
It requires 18 of them, and they just need to be glued to the print (there was no adhesive on the mirrors I received, only thick adhesive pads).

Becareful if you buy the same mirrors than mine, they have inconsistent dimensions (I noticed up to 1mm of difference on the largest dimension).
Hopefully I bought 3 packs (so 36 little mirrors), and I've been able to select the ones that were fitting perfectly.