Thanks ! it was way easier that way !
By the way, i was going to ask you this : “is it possible to make all the stuff with additive block (lets say only the rooms block, withouth sickness), and flip all the normals of the selected objects ? I see the “Flip button” in the edit geometry tab and make it a room that way?”, but i just gave it a try before posting, and it works. And i think it’s even better than the previous method !
Edit: just tried with several brushes, and it doesnt work. Only one will appear correctly