Among the following, which is NOT typically used to create orthotic devices?

Concrete is not typically used to create orthotic devices due to its heavy weight and rigidity. Orthotic devices are designed to provide support, stability, and comfort to patients, and materials like plastic, stainless steel, and lightweight alloys are preferred for their favorable properties.

Plastic is commonly used for its versatility, ability to mold into different shapes, and lightweight characteristics. Stainless steel is valued for its strength and durability, making it suitable for certain types of orthotic components. Lightweight alloys, similarly, provide a good balance of strength and reduced weight, making them an ideal choice for various orthotic applications. In contrast, concrete lacks the necessary flexibility and comfort needed for orthotics, making it unsuitable for this purpose.