There are no size restrictions on the carving of pumpkins. However, we place a plastic cup with candle in each one. The Jack O Lantern should be large enough to accept an 9 oz. plastic cup with ease. Also, the tops should be cut at an angle to avoid the top falling into the pumpkin. Remember, the top will shrink slightly after the pumpkin is carved. The closer to the Jaunt that the pumpkin is carved will result in a nicer Jack O Lantern during the 2 night affair. The longer the pumpkin is opened up, the more chance of the pumpkin starting to mold. Any reasonably carved design will be displayed but we do reserve the right to not display offensive Jack O Lanterns.