The Electronic valves are in fact potmeters with internal springs. I added a copper modeltrainpart on top of these potmeters to add a trumpet look. An (artificial) ivory top layer will be added later. The same copperparts are also used to top off the electronic switches.

Mechanical information:

Material : 8FLP10A potmeter from sakae-tsushin. Messing push surfaces from the model train shop. ivory tops from Atelier Pfeiffer, Den Hague.