Services Service Sin Yang Plastic Enterprise Our Services Full-service plastic company Sin Yang Plastics is your end-to-end, full-service plastic company. We take your concept from initial prototype through production, finishing and delivery. Focus on the plastic hardware needs Sin Yang Plastics focus on the plastic hardware needs and demand from the market trend. Construct a prototype and build custom mold Our staffs of experienced in toolmakers work with you to define your concept, construct a prototype, and build your custom mold. Our toolmaker also can troubleshoot on mold.