This pattern was designed to use exactly one skein of 80% sw merino 20% nylon, 76 yard, bulky yarn. Each dyer seems to have a different way of naming this type of skein from chunky to super bulky. The key is the 76 yards and the fiber content.

You can use ToshASAP which has more yardage or other chunky/bulky yarns. Be sure to check gauge when using other yarns.

Otherwise, here are some sources for this specific yarn type:
Thread Head Knits Co. Single Ply Super Bulky
Hickory Lane Fiber Co Single Ply Bulky
Bella Vista Knits Chunky Single Ply
Tippy Tree Yarns Single Ply Super Bulky
The Sheepy Shire Maizy Super Bulky
Dancing Skies Fiber Arts Chunky

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