If you want to take pictures of small objects at close range, you need a macro lens. Or microscope. [Nicholas Shylock] thought, “why not have both?” He designed a 3D printing microscope lens adapter, which you can find on thingiverse. Recently, [michaelwedell] conducted an experiment with a microscope lens, and you can see the results in the following video.
A $20 microscope lens can take some amazing photos. There are two designs for different crop images and full frame cameras. As you might expect, the depth of field is very thin. When using 4x lens, the width of the image is about 9mm. You must have a stable hand to maintain the focus of all objects.
[michael] also enclose the focal length to obtain several photos, which can be post processed to provide a deeper depth of field. He has a different video, covering the process of his use. You also need a lot of light, because the effective focal length of the lens is f/20.
Manual use may require more patience than most of us. However, if you install the camera in the studio, we can see its usefulness. Again, you can install the camera on a real microscope, but it may not be the price.
The results were impressive. We also noticed that printing in PETG can cause some problems because it is shiny. You can paint the inside of the pipe or use ABS, which is not too shiny.
Of course, you can build a microscope. You can even start with LEGO.