These stretchy handwarmers are an excellent use for a single skein or an extra 2oz. of worsted-weight yarn. The construction is simply a cylinder with a small split. The stitch pattern was designed using a tiny bit of mathematics so the knitter would only need to memorize a 12-stitch sequence but the pattern repeats every three rounds.

Finished measurements (unstretched): 6” circumference, 7.25” length.
Needles: use double-points or two circs or magic loop.
Stitches: just knit, purl, and twisted stitch (for most people, knit through the back loop).
Uses Jeny’s Super-Stretchy Bind-Off.
It is easy to modify the length of these mitts and less easy to modify their circumference.