After reading the discussion here at Microscope yahoo group, I decided to give it a try to the stop filter, and do one myself.

First, a preview of the final results (taken through the eyepiece, with my digital camera):



This ciliate was black/white for me until today!

And that was the process of making the darkstop made of some kind of prototyping plastic (tomorrow I can tell you exactly which kind)

Measure of the filter holder size of my microscope(32.2mm) and drawing with the compasses


Getting a cutter


Cutting the outer circle


Carving with a "multi tool", that will make a lot of dust, so be careful.


Result of carving


Cleaning of the surface


Drawing with a black permanent marker. (I tried without that, but what I got it was a gray background instead of black one)