I wanted to mount my DSLR to an old Olympus VMT microscope. Found a fitting camera attachment (on ThingiVerse) and made a remix with a fitting cylinder for the microscope. Also made one for a cheap Bresser Microscope (but it doesn't produce as good images as the Olympus one).

Print instructions

I printed with a .40 nozzle, .20 layers, no supports, 15% infill and 3 perimeters to make for a very solid attachment. Use very dark filament (or higher infill) to ensure minimal light protrusion.