This thread has given me an idea for a new valve setup style, and one which could be applied to most current trumpets (or horns). Instead of finger button surfaces you press down on, imagine a ring on each valve stem which you insert your fingers into. Now the valves move with your fingers, your fingers won't slip out of the rings unless you move your hand away, and if you could arrange for the rings to be close-fitting, you could probably dispense with valve springs too. Perhaps the rings could be implemented as little straps you can lash around your fingers.
Horns could be provided with a set of buttons or a set of rings and you screw the version you want onto the valve stems.
Anybody know a good patent lawyer?