Sashing can be one of the key features of your quilt. Keep in mind, you can only add sashing to Horizontal, On-point and Variable Point layouts.
To draw your own sash blocks, draw them in a rectangle the size of your sash. To do this, click BLOCK > Drawing Board Setup. Change the size to 12″ x 2″ or whatever size fits your sash. Your newly drawn sash block will appear square in the Sketchbook, but will look perfect when set it into the sash spaces on the quilt. (Half the blocks will need rotating.)