This is less of a pattern, and more of a recipe.

I explain how to make the flat, round bottom (in the size you want, depending on how tight you crochet).

Then I let you know how tall to make the cozy, and how to finish it off. The actual cozy itself can be in whatever stitch you fancy. The sky’s the limit.

Links are included for the Magic Loop start, a smooth finish, and the stitch I used in the pictured cozy.

This has not been test knitted, beyond the single cozy I made for myself.