An old issue of Super 8 Filmaker magazine has an article about installing a 1 F switch in a projector for under 3 dollars (probably about 20 now).This could be used for sync projection as well as real time optical printing for projects involving rear screen EFX work and such.
Now imagine combining this with a Schufftan box and the possibilities are endless.You could even work in forced perspective there and really do some SFX that would be very inexpensive and impressive.Labor intensive though.Anyone ever done anything like this?