Thanks Mark & Ralph. I could have looked for one myself, but having now been spoon fed I'm surprised at the cost. If I did make one I would hesitate at drilling a small hole through a small piece of HSS. I think that would be challenging. I have drills that can put a hole through a file but the 3 or 4mm size drill to hold the cutting blade would be costly and fragile and need to rotate at RPM beyond the speed of any machine I have, or contemplate getting.