The microscope is a "Hetto Klein-Mikroskop" by the Germany-based company "Willy Hettig" and is from some time before the 1940. I know that because the company stopped making microscopes under that name around that time. The microscope tube is a simple optical device with a two-lens ocular and a two-lens objective, and it magnifies by about 100 times.
For the camera, I used the built in webcam of a old DELL Laptop that I converted to USB. The enclosure for the camera is designed in freecad. The files are added below.
Light is added by making a wooden stand with two LED light arms that sit on the same wooden baseplate as the microscope itself.
My video shows the building process, explains how to convert a laptop internal camera to USB (it is basically already USB, you just need to find the right wires and make sure it does not get 5V when it needs 3.3) and gives some cool insight in the microscopic life in some moss samples.