In the early- to mid- 50s, there was a show on television where inventors presented their ideas, looking for funding or customers. I remember one who had a blade control for a gearbox-style Cat grader. (Perhaps that was the only style at that time.) The operator held a miniature moldboard with both hands and moved it in the way he wanted the real moldboard to move. A complex linkage engaged the proper clutches to move the moldboard. I don't think there was any feedback, so when the board got to the desired position, he returned the miniature board to neutral. Did this idea ever get to the market? If you have a better memory than I, please fill in the details.