Kuttrolf stem

(German) A flask with the neck divided into two or more tubes. The Kuttrolf, which has Roman antecedents, was produced by German glassworkers in the later Middle Ages; it is also found among Venetian and façon de Venise glasses of the 16th and 17th centuries.

Twisting stem
Wineglass with Kuttrolf Stem
Wineglass with Kuttrolf Stem short video focusing on single technique