Ole, what do you intend to use for a shutter?
Originally Posted by Ole
I made the tandem rig instead of building a monorail incorporating my 2x3 Speed with (a) a moveable front standard or (b) a rack and pinion device for moving the Speed fore and aft for focusing. The monorail seemed much harder and more expensive to realize.
The potential problem I see with your Aerotar is that the rear node (or perhaps I should have said exit pupil) is ~ 10 cm in front of the back of the lens. You'll need to put the shutter as close to the back of the lens as possible to reduce the chances of vignetting. Reasoning from similar triangles, if the shutter is at the back of the lens, to cover the format you need a shutter whose diameter/10 cm >= 150/500, i.e., whose diameter wide open >= 3 cm. So a #1 will just do, and larger would be better.
How big is your Reisekamera's lens board? If its front standard will bear the load, you might make a tube out of PVC pipe. Stronger than a coffee can, easy to machine.
Good luck, go on having fun,