Because the main material, zelkova wood, has been insufficient from domestic production in recent years, shioji wood (Fraxinus platypoda) mainly, or sometimes quince (leguminous), and oak from overseas are used, with using these hard woods, a swollen hollow cylindrical trunk is made by hollowing out a timber or by assembling the boards together.
ケヤキが主であったが国産は近年不足しているためシオジ・ハリギリが主流、また海外からはカリン(マメ科)・ナラなどの堅い木材をくり抜いたふくらみのある円筒形の胴、もしくは板を寄せて円筒を作り桶のようにしたものを用いる。