I had an unusual instrument that had special locking mini-switches. They way they worked is that the switch lever was spring-loaded (the spring pulled perpendicular to the face of the instrument) and there was a special slotted piece at the bottom of the switch lever. To flip the switch, you have to lift the lever up over the bumps at the bottom, then you drop it down to lock it into the new position. The switch lever had a screw on piece that was sort of rocket-shaped (easier to grip than a normal toggle).
I think this was probably some sort of aerospace part. I remember seeing larger versions of this kind of switch in a light aircraft cockpit. The hole for the switch was probably a little bigger than your regular mini-toggle, but not by much.
These switches were on a Hamer 12-string bass that I bought from Rick Neilsen (the guitarist in Cheap Trick). I don't know if they were there when the bass was built or added later (I would guess the latter). The bass had two pickups (oddly, they were DiMarzio X2N guitar pickups, but hey, the instrument was only 1/3 bass!), and the each pickup had it's own preamp. The special switches selected low boost level, high boost level, and a bright boost. There where independent volume controls, no tone controls, and stereo out. There was also a battery switch and LED.
If I ever find those switches, I would buy a ton! They were great. I don't even know what to call them unfortunately.
David Fung