Jobs at small Wichita companies nobody posts about - 7 months and counting

A friend who works at a local manufacturer says there are openings not advertised online. It has been a long 3 weeks. One is a print shop, one is an accounting firm and one is a clinic. What do you write in a cold email?

A short email with two sentences about what you can do and your résumé attached worked for me. I followed up after a week.