Rigid resin is reinforced with glass to offer very high stiffness and a polished finish. It is highly resistant to deformation over time and is great for printing thin walls and features. The material is comparable to other glass-filled thermoplastics. When considered along parts printed with other resin materials, those printed with rigid resin resist mechanical stress over a longer period of time. Stiffness is a measure of a material's resistance to elastic deformation under stress. Due to the high degree of stiffness, rigid resin parts are more brittle than parts printed with tough or durable resin.