Sourcing a shutter

[Harlan Chapman]

I'm looking for suggestions on the best way to source a cheap, bare working shutter that I can mount on a lens board for my 5x7. Want to stuff an f45 zone plate into it (functionally it is a piece of film taped to a piece of cardboard). The zone plate is only a few mm wide so the shutter doesn't have to be big. Exposure times are quick enough that an adjustable shutter would be a real convenience. I'd like more flexibility in setting speeds than I can get from my 3" Packard...
Not sure where to start here, your thoughts appreciated.
-Harlan

[Kirk Fry]

Ebay, look for damaged lenses with good shutters. Usually these are lenses with damaged front lens rings (dropped). A while ago 240mm lenses sold for much less than their naked No. 3 shutters. Given that no new shutters are being manufactured, jump quick.