[Harp-L] where to get valves for half-valving a diatonic

[Dan Hazen <bluesmandan76@xxxxxxxxx>]

I'm not making much progress with my overblows. I've tried arcing and
gapping etc the harps, but can only get a moderately reliable overblow out
of hole 6. I'm using mostly suzuki bluesmasters and hohner meisterklasses.
I'm thinking about trying out half-valving to see if it gets me better
chromatic-like results. I've never added valves to a harmonica, though.
Where is the best place to obtain them? And are there some good diy videos
or websites to walk you through it?