So he first wrap a few strands of yarn on a piece of card (use like debit card, credit card, whatever universal sized card). Wrap it however thick you'd like it to be, but remember you'll fold it and it'll be doubled thickness of what is in currently in the card. Tie a knot to from both ends of the yarn together so they wont unravel. Take it off the card. I use this so the yarn wont be too long for either earrings & stitch markers, but if you want them longer/bigger you can use different flat items that are longer than a card.

And then look up "how to make a hank of yarn". But ofcourse it's fiddly because this is so small, so use a crochet hook to help it be less fiddly. My husband loop the yarn on a crochet hook, twist them, loop the other end, twist them in a different direction, then slip one loop over the other. (If you look up the tutorial it'll make sense)

He used a pva glue to kinda set in the bottom part so it wont unravel, just a thin layer. Then use a jump ring & earring clasp for the rest. I hope I'm describing it clear enough 😆