The advent of 3D printing is transforming the manufacturing landscape, enabling flexible, on-demand production with minimal setup costs. This study examines the impact of 3D printing on the manufacturer-retailer supply chain, focusing on a Stackelberg framework with two product scenarios. We analyze the conditions under which 3D printing becomes a viable alternative to traditional manufacturing, considering factors such as customer demand, production costs, and capacity constraints. Our research highlights the complex trade-offs involved in adopting 3D printing, including reduced inventory holding costs, improved customer satisfaction, and increased flexibility, versus higher variable costs and slower production rates. We also explore the implications of 3D printing for supply chain coordination, including the potential for double marginalization. The study contributes to the growing literature on 3D printing in supply chains, offering actionable recommendations for businesses navigating this evolving landscape. Our findings provide valuable insights for manufacturers and retailers seeking to leverage 3D printing to improve their supply chain operations and stay competitive in today's dynamic market.