While drawing a block perimeter, you can select the block form from the Drawing options data panel in the bottom left of the screen. The standard block forms are provided to facilitate the creation of blocks representing specific building geometries. You can select from options 1-4 below:
The 5-General block form is not selectable but rather is defined internally by DesignBuilder following block geometry operations such as Cut block, Horizontal block extrusion, Drag face and Boolean geometry operation.
Once a block has been created, it is possible in most cases to change to a new form by navigating to the block and opening the Model options dialog. When at block level the Model options dialog opens at the Block tab and there the Block form can in most cases be changed.