Thanks guys, I am off to hardware store with ideas and measurements. Third Eye Mirrors sit on a 1/4" 24tpi threaded post. Going to see what I can find. My friend has a machine shop/mill etc . Thinking he can help me fab a tap to glue on helmet, with insert or tap and thread for the mirror. I have multiple pairs of glasses, all with different temples, so the glasses mount is not in the cards.