Mounting slides is easy. There were plastic clip-together mounts like Gepe and Wess (?). Then Gepe also offered anti-Newton glass mounts, which would be more work. Standard mounts were cardboard
clamshells which you simply dropped the film in and sealed along the edge with an iron. Took just
a few seconds apiece. If you didn't want to use scissors, there were inexpensive little plastic slitters
you could feed film thru an easily shear it. Probably this kind of gear is still around, if not still mfg new. Labs around here still routinely mount slides, so must still have a source for the supplies. But
you don't need any kind of fancy automated gear like they use. Mounting a slide is far easier than
making a sandwich for lunch.