I need to know how to activate subtractive brushes it if its available in Unreal 4.12, because I need to create hallways and doors and need to CUT holes into solids to create the hollow areas I need, hollow squares, hollow cylinders, and in the earlier versions it had this option (known as Air Brush in Red Editor) but in Unreal Engine its called a Subtractive brush).
But when I look in Unreal 4.12 I can’t find it. At the moment all I can do is just shape static solid mesh brushes. I can’t cut any holes in them, because there’s no air cookie cutter brush for me to use that I can see of to beable to cut the holes I need. So how do you cut holes in your basic solid shapes?