Game Development Reference
Now select the blue addiive brush in one of the 2D views and move it to the side.
The checkerboard cube didn't move with it. When you modify exising the CSG,
unreal requires you to rebuild for a simple cube move, which is prety fast. But when
you've got a whole level roughed-out in CSG, you wouldn't want unreal to pause
and re-calculate all the ime. Click on Build Geometry for Current Level , towards the
top-right of the screen. You'll get some warnings, which are no big deal—that we'll
discuss later—but the cube appears where it should appear.