The Tanko existing now are mainly made of iron or gilt bronze, however, some pointed out that it is possible organic material was also used to make them and various Tanko made of organic material such as wood, leather and knitted plant fiber with lacquer on it were unearthed from the remains of the late Yayoi period in recent years.
現存するのは主に鉄製や金銅製のものであるが、有機質材料が併用されていた可能性が指摘されており、近年は弥生時代終末期の遺跡から木製や革製、植物繊維を編んで漆を塗ったものなどさまざまな有機質材料の短甲も出土している。