35 mm Slide Viewer, customizable

Many of us keep a large number of 35 mm film slides from a distant past. There were some simple and inexpensive gadgets to see the slides without a projector. Today is difficult to get one. Online you can find some slide viewers far more complex, heavy and expensive. For this reason I designed my own slide viewer and built it using a small lens from my junk box. It is likely that you can get a different lens and for this reason my design is customizable.

You can use a lens savaged from a small magnifying glass or a loupe or a scraped optical device (mine came from a cheap ramsden eyepiece that belonged to a small telescope). The lens should have a focal length between 45 and 65 mm. The focal length is the distance between the lens and an object to see it well focused. As for the diameter anything from 10 to 38 mm can be used.

The viewer consists of three pieces: a body, the back piece and the lens holder or focuser. The back piece is always the same. There are two focusers, one w