It's not that big. About 15"×15"×6", I'd guess.

The autoload mechanism is pretty much the same mechanism on the slide projector we had in the early '80s when I was a kid.

I don't have the 100-slide magazine; that's the toroidal one. I just have the rectangular 50-slide magazine, but that's good enough. I have most of the slides in similar toroidal magazines that fit in the slide projector, but, sadly, they don't seem to work in the scanner.