I have the whole Tektronix C-53 camera (currently only using the oscilloscope back) so I essentially have the shutter and control board, it would just be a matter of cutting the thing up. I already figured out the input voltage on the power input pin (15V) and have an old 16V power brick from a broken HP printer, so I can and have operated the shutter.
SMBooth: I like the pinhole shutter idea. I just bet that it will burn battery power while it's left open but it sounds like if I can get the control board to do what I want it might be great for <15sec exposures. Then again I have an old Polaroid with an "automatic" semi-electronic shutter and it would probably be easier to just use that since it runs off of 3v and I can control the speed of it by replacing the CdS cell with a potentiometer (theoretically anyway.... I haven't actually done it yet.)
Be a lot simpler and more reliable to use a lens cap. Or a bit of black tape.