Walt Bennett
After ten years of selling at these kind of shows I've settled on first making certain they're given a card with contact info. Since I don't make museum pieces, I've also gotten to the point of only using tung oil for a finish - durable, waterproof, food safe and easily repaired. This because no matter what precautions I give them (including "not dishwasher safe"), a given buyer may hand it off the next day to someone else and forget to pass the info on. The more complex the instructions (even if written down) the more likely they'll be ignored or forgotten has been my experience.