3D printing services are appearing, allowing consumers or businesses to order custom parts for delivery within a quoted lead-time, regardless of design specification. The manufacturer’s problem is to ensure that customers receive their goods on time, while capacity costs (including overtime costs) are kept low. We introduce a performance measure called the service rate, analogous to the fill rate of inventory control. Using design science, we identify and evaluate order book control policies to manage the service rate - capacity cost trade-off. Our results show that production smoothing is compatible with high service rates for customized products with short delivery times.