Katana sheaths, also known as saya, are typically made from wood. The type of wood used can vary, but traditional materials include lightweight and durable woods such as magnolia (ho wood) or Japanese white oak. These woods are chosen for their strength, flexibility, and resistance to warping or cracking.

The wooden sheath is usually constructed in two halves that are carved to fit the shape of the katana blade. The two halves are then glued together and reinforced with metal or bamboo pins. The inside of the sheath is coated with a layer of lacquer to protect the wood and facilitate smooth insertion and removal of the blade.

In addition to wood, other materials may be incorporated into the saya for decoration or reinforcement. This can include a layer of ray or stingray skin (samegawa) that is often wrapped around the mouth of the sheath near the opening. The skin provides grip and adds an aesthetic element to the saya. Furthermore, a cord or braid (sageo) is often attached to the saya for securing and carrying the katana.

It's worth noting that modern katana sheaths may deviate from traditional materials and techniques. Some contemporary sheaths may incorporate synthetic materials or alternative wood types, depending on the desired aesthetics, cost, or specific functional requirements.