Other vendors are not necessarily your competition, you compliment each other. If a customer asks if you make bowls with purple elephants, say, “No, I don’t but there’s an artist in aisle 4 that does. You can mention I sent you” and give them your card. If you have time even walk the customer to that other artists booth and point out the items. If you just say, “No, I don’t make that”, what reason have you given that customer to remember you? And that other artist may just get a request for something you make that they don’t and will send people to your booth. Also that customer will stop at your booth every show and bring a friend to meet the nice person that helped them.