Hello ! I’m glad my little experiment aroused so much enthusiasm 
I will ask them next week if they could print a batch, like 10 or 20, then I could send them by (regular?) postal mail to interested people…
Unfortunately, on this specific 3D printer, only 3 color are available : grey, white and transparent…
The cost of using this 3D printer is 8€/hour and it took around 3h, so I paid 24€ (excluding the inscription fee).
It’s one of those 2 ones (have to check) : formlabs
It’s advised not printing perfectly vertical, but little inclined instead, to avoid some deformation at the edges.
A pending question is durability: I have no clue on how long this new cover will survive…
The guy was advising to protect it from UV, though, as the resin is polymerized with UV light in the 3D printer…