If you are making hard surface objects in 3D-Coat, I recommend using other 3D-Coat tools instead of brushes. For example use Boolean type operations such as the Carve Tool with "Invert tool action" checked and then use the rectangular selection method in the E panel or the curves method. You can get very clean straight cuts on your model this way. I also recommend creating object shapes on one voxel layer and then right click on the layer and choose "Subtract from..." or "Merge to..." from the pop-up to get clean additions or subtractions from your model. Kitbashing techniques are also good for hard surface
In general I feel the brushes are just not very good for hard surface stuff (although they are improving as time goes on).
Hey thanks for the tip! I recently have been getting more comfortable with the carve and various curve options. I do agree that for the most part the brushes are not very good with hard surfaces. However, the flatten clay brush seems to be pretty good at times.
Wouldn't it be cool if we had a sort of "revolve" option for some of the curves for the carve tool? I noticed you can save and edit curve points on the "closed spline" option. A revolve option would be cool if someone wanted to create lets say a scope for a gun or an hour glass.