Mechanical behaviors of a new class of composites made up of a 3D textile core enclosed by two rubber layers, either reinforced or unreinforced, are investigated in this study to address the need of lightweight and durable structures for non-pneumatic tire applications. The manufacturing versatility of 3D textiles offers incredible possibilities to engineer these composites for targeted applications. However, building a composite with these textiles following the conventional technique comes with several challenges. Mechanical testing of these sandwich structures considering different topologies of the reinforcement textile is also complex. Initial efforts to characterize these composites using existing testing protocols resulted in unexplained features. Therefore, it is of interest of develop methods to build durable composites as well as to test these composites. To this end, a novel curing method has been developed to build durable coupons successfully and reproducibly along with a test method to characterize these composites. Lab coupons comprised of 3D textiles of different forms were built and tested for their mechanical characteristics keeping the end applications in mind. Building defect-free durable composites is the most critical step toward screening materials for tire applications, and the solution proposed through this study will surely enhance this effort.