One of the keys to creating small plastic parts that are free of cosmetic blemishes is consistent wall thickness. When wall thickness is not relatively uniform throughout a part, the plastic cools at different rates, and problems can occur. Thin wall sections in the middle of a part can be especially problematic, as they lead to improper filling and issues like sink and warp. But, by following a few guidelines, you can ensure that your parts are both visually appealing and functionally sound.