If you've read my other thread today you will see I have brought a part to work to study. Whilst waggling my fingers in mid air, it struck me that I have never seen any kind of dummy valves for practicing. It then occurred to me that such a gadget could encompass switches and be used to compare the valve operations to a pre-programmed sequence to give an assessment. If every operation were compared by a microprocessor to the music preloaded, any bad fingers could put a red light on so the user could see they made a mistake. Does such a thing exist? If it does or did, would it be used?