Game Development Reference
Time for action - the builder brush and our first cube
At the center of your empty level is a red wireframe cube. This is the builder brush. Think of
it as a rubber stamp. Whatever shape and size it is, that's the shape and size of the geometry
that you're going to stamp down.
Select the builder brush, then click on the CSG : Add buton.
This stamps a cube down into the world, as shown in the following screenshot:
If you move the builder brush out of the way, you see that the cube stays in the 2D
views. It appears as a blue wireframe box.