This is a great project if you love to drink out of glass but hate dealing with all the sweating. I have used these kinds of insulators for 2 years. They work great for keeping water colder longer and reduce watery messes. You can reduce the size to a pint if you felt the project.
I used the 3/8” gauge x loom but I also have written for regular 60 peg loom version in the same gauge. There is a video tutorial for the x loom version but written for the regular round 60 peg 3/8” loom version.
This is also a great project for some scrap worsted yarn. You will need 3 to 4 buttons and if you are doing the round loom version you will need a thin elastic to put through the cast on.