Quote Originally Posted by DWThomas View Post
You didn't describe exactly how you made the pinhole, the actual mechanics may affect the quality. The method described here has produced the best results for me. I have used #600 grit wet-or-dry sandpaper wet, with gentle pressure and circular motion to do the sanding. My last one was blackened with a liquid used in making brass model railroad parts (some sort of sulfide chemical).

Ok, I cut out a square from can..than i grinded it and make a hole on my first attempt.
Thanks for link, I will try it