This study develops an environmentally sustainable inventory system for retailers engaged in the sale of recycled plastic products derived from the reprocessing industry. The model integrates an investment framework in additive manufacturing technology aimed at minimizing emissions and waste during production while simultaneously enhancing product quality. The main objective of the proposed inventory system is to elevate the quality standards of recycled products and improve overall profitability. Furthermore, the model incorporates demand-dependent reliability, pricing, and quality factors to maximize profit while satisfying customer demand. It also considers deteriorating items, potential shortages, and trade credit policies to ensure a realistic operational structure. The applicability and efficiency of the proposed proposal have been exhibited through a case study involving an existing retailer, confirming its capability to enhance profitability while promoting eco-friendly production through additive manufacturing. The results indicated that the incorporation of additive manufacturing technology led to more than 2% improvement in total profit for the inventory system. Moreover, a sensitivity analysis was conducted to assess the influence of key parameters on the optimal solution.