A simple cozy pattern for a coffee mug. I purchased a coffee cup from JoAnn’s for $5.99 and used Lion Brand Fisherman’s wool (approx. $10 for a skein of yarn) that will make a lot of cozies. I used this to make Christmas presents for my employees.
Use size 8 double pointed needles (I only used 4).
Cast on 45 (15 on 3 DP’s) working in the round
Knit 3, Purl 2 for 26 rounds
Bind off (make sure to be loose)
That’s all 
Here’s a picture of the finished product.
I'm adapting your pattern, adding a cable or two.