Recycling systems serve the dual function of being both the means for waste management as well as the means for producing recycled materials. Any recycling system is subject to various conditions, including the amount of waste generated and the demand for recycled materials. Due to the fact that these conditions have variability factors, they may be connected to diverse variation risks such as a lack of recycling facility capacities. In this paper, applying the concepts of robustness and flexibility that are utilized in process control and supply chain management, we construct a framework for a recycling system design that incorporates robustness and flexibility against variation risk. Requirements for evaluation indicators of the recycling system are discussed, and robustness and flexibility indicators are defined. A method for alternative generation based on the evaluation of robustness and flexibility is then also presented. The framework has been applied to a case study wherein PET bottles are put through a domestic recycling system. Alternative systems are then evaluated and developed by means of design change in certain elements, including facility capacities for respective recycling technologies.