If each pumpkin was passed down a conveyor belt in a single file line then it's diameter could be easily measured with an array of light sensors aimed verticall

If each pumpkin was passed down a conveyor belt in a single file line then it's diameter could be easily measured with an array of light sensors aimed vertically which could be used to set the price in the checkout system. Different customer's orders could be separated by a board that spanned the full width of the sensor array, which would stop the conveyor until it was removed.