I guess most of you would have been frustrated not having an exact size crystal for pocket watch repair. I got an idea from a tool I saw on eBay and made a simple sizer. I have found it works really well. Using a slip fit cement chuck I had on hand I bought a 10mm bearing from eBay ($1.49) and in the first picture you can see that I made a small cap to fit over the bearing from 12mm aluminium rod, I used some lock tight to secure it with an interference fit and them turned down a cement chu