I wrote a free pattern for a scrunchie knitted either with 2mm, 3mm or 4mm double pointed needles and some yarn leftovers. You can find the pattern on ravelry (link in comments)
Free Knit Scrunchies Pattern – Update – Savlabot
Free Knit Scrunchies Pattern – Update – Savlabot
Free Knit Scrunchie Pattern — CLICKETY STICKS
Knitting tutorial : Duo of gourmand scrunchies | Knit On
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NORDIC KNIT SCRUNCHIE | Boes Ltd.
Knitting Kit - Mini Mohair Scrunchie - Lauren Aston Designs
How To Knit A Scrunchie Onto A Hair Tie - plus a little knitting chat - YouTube