Still on the subject of sketching, Rhonda offers one of the best options for 3D ideation on the screen. Finding an efficient and intuitive interface is key: on the one hand the program can't make so many assumptions that it gets in the way of what the user wants to do, on the other requiring them to make too many choices is equally distracting. Perhaps a continual gradation between the two, changing naturally as one racks up hours in the program.
