I am looking for the twin slide carrier for Mamiya Procabin 67z slide projector. This holds two 6x6 or 6x4.5 slides that you slide in and out of the projector sideways. I can watch the 6x7 slides and the negatives using the projector, but would like the option to drop in a 6x6 slide as well.

I have searched everywhere and not sure where else to look. Any help or suggestion would be highly appreciated.