OK yeah these Snaptron "domes" are what I was thinking of:
**broken link removed**
But I'd need an off-the-shelf low volume source... maybe even some cheap dollar store item I could rip apart. Wouldn't be the first time!
The DX parts: no, for several reasons. One most of those are latching switches, I'm going with momentary. Two, they're not very flat, even the NDS lite switch. I have a 1.75" cylinder that needs a momentary button on the curved side not the flat ends, and without enough room inside to mount a switch inside the body. Also how the switch is even going to be retained would be a problem. The outside is going to be leather-wrapped and I'd rather not have a button sticking out at all.
So my idea is one of these domes here glued to the outside, a couple of thin wires routing back inside, and leather over that so you just feel for the switch.