How i can subtract with the brush an imported mesh for a 3D Software. This is exactly what i want, i’ve created a modular walls etc and i don’t want to create a modular wall with windows to each type of wall, there’s anyway than i can substrack with the brush an imported mesh? It’s even possible? Thanks you 
You can only subtract brushes -> it doesnt work with meshes
Then i need to make modular windows for each type of wall? D:
Yep, you have to do that in your 3d program
Hmmm thanks you ^^