I made one of these and use 1/16″ cobalt drills in a small drill press. You could hand drill in a vise also but since I have the drill press that’s what I use.
Not sure if I’m lucky or good but I’ve drilled a ton of bolts, both stainless and high tensile, and haven’t broken a drill yet. I can drill a bolt in literally 30-45 seconds and unscrewing the bolt from the jig deburs the threads.
I have a drawing I can share if anyone is interested.