The original set of pages is unavailable, but they can be found at the Internet Archive at:

• Klein bottle hat PDF
• Lettering instructions
• Knitting One-Sided Surfaces

Yarn is not specified but looks like dk or worsted-weight in the photos, and given the nature of the garment. No gauge given, but 88 stitches fits 24” circumference. Recommended to adjust for wearer. Yarn requirements given as two 5-oz skeins.

Four dpns recommended, plus a fifth for increasing if desired.