The saya, or scabbard, of a katana is typically made from wood. The most commonly used wood for crafting a katana saya is Japanese honoki wood (magnolia obovata). Honoki wood is chosen for its lightweight, durability, and resistance to moisture, which helps protect the blade from rusting.

Crafting a saya involves carving and shaping the wood to fit the specific katana it will house. The wood is hollowed out to accommodate the blade and is usually lacquered on the inside for added protection. The outer surface of the saya is also coated with lacquer, which enhances its appearance and durability.

The saya may be left plain or decorated with various designs, such as painted artwork, lacquer work, or inlaid metal ornaments, depending on the preferences of the sword owner or the specific style of the katana.

It's worth noting that there are variations in saya materials and designs across different historical periods and schools of swordmaking. Some modern katanas may also feature saya made from alternative materials such as synthetic polymers or reinforced plastics. However, traditional wooden saya remain the most common and traditional choice for housing a katana blade.