Reducing paper waste and increasing resource efficiency has become a priority in the offset printing industry. We consider the production process of a company that prints customer-specific designs on napkin pouches. The planning problem consists of assigning the designs to slots of some printing plates such that the demand for each design is met, all technological constraints are satisfied, and the total production costs, which include setup and waste costs, are minimized. The main contribution of the paper is a matheuristic that takes advantage of the fact that the demands for individual designs are a multiple of a minimum order quantity. In a computational analysis based on real-world problem instances, we compared the proposed matheuristic to an exact approach. The matheuristic consistently outperformed the exact approach in terms of solution quality and running time.