Personalized 4' x 4' 4mm Foldable Corrugated Plastic Signs. Your design will be printed in one color on one side of the sign. Vertically fluted corrugated plastic material is sturdy, weatherproof and reusable. Your sign will be scored down the middle which will allow it to fold in half. Folding the sign in half means lower shipping cost, and easier storage for long term use. We will provide you 2 stabilizing spines to secure the sign into it's finished size.