I shoot 66 and 67 slides and view with a manual 66/67 Hasselblad projector (a rebadged Leitz 66 Prato). One disadvantage of 120 slides is buckling , thus requiring glass mounts. My cache of 67 mounts is dwindling. It would be exciting to shoot 69 with my Medalist but where to find a reasonably priced projector and glass mounts?
However, I do shoot most of my slides in 35mm. I have a lifetime supply of Gene mounts.
Come to think of it a 45 slide mounted in a back lighted frame could be interesting.