These are some hand warmers I crocheted about a year ago. They are very handy (pardon the pun!) for keeping my hands warm but still letting me do things.
I made them from a brown acrylic I bought from Lincraft and adapted them from a pattern I found. I think I used a triple crochet stitch (depending on where you are from), but as it was my first time crocheting I didn't take much notice of the stitch.
They are super easy to make, just crochet two rectangles and then join the ends to make a tube, leaving a gap for your thumbs.
When I made the thumb holes, I did it before I joined the ends by stopping my original stitch and doing a chain for a bit before joining again and doing my original stitch. I then finished with a few more rows of my original stitch before joining it.