Cheapest way to make a Bokehmaster What you want is a manual iris extension tube for a MF camera with
focal plane shutter. Pentax 67 works, Pentacon, etc. I don't know if
the ExWarpac cameras are any good, even with upgrades.
You can then cut it down to the proper length and take an aluminum
plate and attach it to the front via welding or epoxy. If you had a
mill-drill or lathe friction welding might be an elegant method. You
cut it down, and you want to retain a reference for center.
The lens assembly is from, classically, a Polaroid Highlander camera.
This will be an 80, 80A or 80B. Best is to find one with a serial
number preceded by the letter L. The cameras have no value.
The shutter is a two "speed", B and I monoleaf that can be
discarded.
Do look for the filters that come with these cameras if monochrome
photography is your goal.