I'm designing a series of aides memoire for my colleagues to contain key details about our legal powers. I'm working on one version to be printed in business card format and another to be printed (either digital or offset) on plastic credit card-style cards. There's a fair bit of text to fit in, even once it's all trimmed down.
How can I work out the smallest font size I can get away with while maintaining readability, given that the printing method will probably differ from printing on paper?