The author did not give much information in the way of supplies other than it is made with “dishcloth cotton yarn.”

From the site:
They measure a generous 9″ wide and 7 3/4″ tall (widest points, excluding handles) and are a double layer for extra protection (you make two pieces per potholder and sew them together). You can line them with extra padding if you wish (I didn’t). The teacup handle functions as its hanger.

(made with dishcloth cotton yarn)

Source: This pattern is based on a vintage pattern from 1943 that was designed to use crochet thread, I’ve made some tweaks so that it will work with today’s dishcloth cotton yarn.