Although izutsu is often made of ishigaki (stone wall) of nozura zumi (laid with mostly unprocessed natural stones), it was made of wood materials in ancient times, including magemono-izutsu, which is also considered to have been used in ancient times.
井筒は野面積みの石垣などが多く用いられるが、古代は木材を使用しており、曲物井筒もその方法の一つとして古代から用いられたとされる。