Vertex Manipulation
 

The vertices of any primitive object may be individually moved.  To enter vertex manipulation mode, select an object and pick the Edit>Select Vertex menu.  The object vertices will be highlighted in both the 2D and 3D viewports:

 

 

 

Click on a vertex and drag the mouse to move vertices.  Multiple vertices can be selected by holding either of the Control keys.  If you have all your vertices selected, and want to move them without clicking and changing the selection, just hold Control  and drag anywhere in the viewport.

 

 

There are two rules that must be followed when manipulating vertices.  Due to the nature of brush geometry, objects must be convex and faces must be coplanar.  Concave means the object has “dents”.  The objects below are all concave, and may cause errors if CSG operations (carve and hollow) are used with them:

 

 

The objects below are all convex, and are all okay:

 

 

Coplanar means that all vertices of a face lie along the same plane in 3D space.  The object below is not coplanar.  The top face clearly lies along two different planes, and parts of it face different directions.  (Can you tell if this object is convex or concave?)

 

 

The object above is concave.  However, convex objects can still have faces that aren’t coplanar!  Although the top face is tilted, all vertices in the object below still line up along the same plane, so it is coplanar:

 

 

If this is confusing, practice moving vertices around and looking at different objects.