吹き矢筒 specifically refers to the tube part of a blowgun, but it is rarely used nowadays.
Standard kanji spelling for this rare term.
Variant spelling without the okurigana き.
Compound of 吹き (blowing) + 矢 (arrow) + 筒 (tube). The exact historical derivation is uncertain, but the components transparently describe a tube for shooting arrows by blowing.