As I side note (quasi-related), if it's of any help, I've found that having some distance between the mic and the source for things like buttons and switches help - it seems that the proximity effect causes it to sound unnatural and hard to 'undo' in Post, but even so much as 1-2 feet of added distance helps it have a natural sound by letting the sounds it generates to 'breathe' within the air.
So on that note, probably a large diaphragm condenser is what you want rather than a shotgun-type mic so that you maintain optimum S/N wile still allowing you some leverage on mic placement/distance. They tend to have a much lower self noisefloor and I've captured some great small sounds with one before (like Blackberry keys), and I was able to boost the recording quite a bit in post to master it hot and there was still virtually no detectable noisefloor. Granted, this also matters what type of preamp you're running the mic into as well - in this case it was an mBox2. Not the best preamp out there, but miles beyond my Zoom H4n in my opinion.
This is only my personal experience though, not a definitive answer - and there's likely many valid solutions too. I've just personally had good luck recording 'small things' using large-diaphragm condensers - things like the C414, U87, NT1A, et al. There's an Octava large diapgrahm too which is quite good from my recollection of using it, I just can't recall which it was, it had a round tubish shape like the C4000.