I'm removing the part for the left wall.
I have noticed that the holes in the walls of the enclosure are not symmetrical. I have used a hole for the spool holder which does not exist on the left wall.
You will need at least two M3 screws and one M3 nut (see picture):
If you installed enclosure handle, the M3x12 that holds it is long enough to secure the HCW module in addition to the handle. Otherwise you need another M3x8 (or longer) + M3 nut combo.
It wasn't my intention to cover the whole side of the enclosure and it is impossible to print a HCW segment bigger than this one on a Prusa Mini.
No supports are needed.
I suggest printing with the outside (visible) surface on the plate so you end up with the nicest possible finish. I made sure the holes for screws will print fine without supports – see picture.
The author remixed this model.
Differences from HCW
I also referenced mounting holes using the assembly model MINI Enclosure Printable Parts but I don't believe it counts as a remix, so using @RostaP's CC-BY-NC license is OK.