My initial thought about the actuator is that it still sounds kind of leaky.
Yeah, it really does, doesn't it? I tried to find rubber coated steel bearings/balls but had no luck, thinking such a thing could be used to seal it better. Perhaps if the idea of a cutoff nail were used instead of a ball bearing, you could dip the nail into some silicone glue?
Also - I'm not sure if minor occasional drips, at least for a homebrew system would matter in the end. As long as it wasn't a steady drip, nor a stream, it probably wouldn't overall matter (think of it as a bit of 'static' in the display).
But I am not trying to defend my design; it was the best I could come up with in a very short amount of time. Maybe a two-way magnetic driver, with a second coil around the bottom of the tip, to draw the ball downward to seal the tip? It would be current intensive, but possible...?
