I continue to make changes. I'm worried this box isn't really clicky enough. Glowy, yes. But right now besides the haptic feedback, there really isn't a true click.

To try to solve this problem, I have been experimenting with relays. Not for their switching capabilities, but for their ability to make noise. After a trip to the MIT Swapfest, I returned with a half dozen 6-24V relays and spent an evening driving them in different ways.

Its clear that the bigger the internal mechanism (and presumably the springs/coil), the louder it gets. In fact the loudest one I have seems like it practically was intended for use a a turn signal. But its way too big to put into a tiny toy. On the other hand, I have a few tiny SMT mounted relays from Omron that are tiny, but have a barely perceptible click. Then, strangely, some relays punch way above their weight. For instance, I found a tiny 24 volt relay that has an impressive click despite its tiny size.

So now its looking like I have a tradeoff to make. I definitely want a relay in my project, but I need it to fit. I looked into solenoids but sadly none of the tiny ones I have seem to be push/pull. So it turns out that the original 5V relay I had in my toolbox all along seems to fit the bill.

I also discovered that you can get louder clicks if you overdrive the voltage. I'm sure this is not good for the relay but since the actual duty cycle is so short, I'm going to risk it.

After a bit of hacking I ended up with this:

I'm using a 12V step up power regulator from Pololu, switched with a oversized N-channel MOSFET. I didn't have any fancy flyback diodes around ( am I supposed to use a "schotty"?) so I just soldered the ones I had.

The result is a nice clicky sound now that you can feel in your hand.