My kids (15 and 11) open carry under the "educational purposes" exception provided under 2923.21 (A)(3). And, as per Federal law, they have my written permission on them while carrying, even when I'm the supervising adult.
eye95 is right. It seems the only way to legally "furnish" by sale is if the recipient is a LEO. I assume MP's or other law enforcement officers would qualify, but that's probably up to the base commander (or higher).