Now that I've done it, I would say that arm knitting's relationship to traditional knitting is similar to finger painting's relationship to fine art. Both are capable of producing lovely results, one is just a lot more precise than the other.
Arm knitting and traditional knitting utilize the same general principles -- casting on, binding off, etcetera -- but arm knitting is inherently freeform; it simply can't be as exact as traditional knitting. The size of a knitter's arms varies greatly from person to person, and even on a single knitter's arm the forearm is usually quite a bit wider than the wrist, so it's nearly impossible to make sure all the stitches are identically sized. However, each stitch is so large that the final result is incredibly malleable and all the stitches shift and even each other out once the project is complete. Also, the process of arm knitting feels much more like moving loops from side to side than winding yarn in specific ways to create perfect stitches as you do in traditional knitting; it still feels like you're working with yarn, just in a very different way. Having said that, I have become a fan of this inexact science, and I'm excited to share my arm knitted Triplet Shawl with you.
I learned the basics from a Michael's youtube video, Arm Knitting for Beginners, which was straightforward and quite helpful. It covers how to cast on, make the basic arm knitting stitch, and how to bind off. If you've never arm knitted before, I highly recommend watching that video before you move on to attempting the pattern below.
All the other arm knitting patterns that I've seen on the internet are for rectangles so there's only one type of stitch necessary with no increases or decreases. I didn't want to make a rectangle, though, I wanted to make a triangle. To do so, I decided to go with the easiest decrease in traditional knitting: knit two together. To knit two together arm knitting-style, I simply slipped two loops off of my arm at once and kept on truckin' as if I had only slipped off one loop, thus decreasing the number of stitches in the next row by one. Here's what that looks like:
Keeping all that in mind, here's the pattern for the Triplet Shawl!
5 skeins of worsted weight yarn in complimentary colors
Cast on 28 stitches, using all 5 strands of yarn together as if they were 1 strand.
Row 1: knit
Row 2: knit 2 together, knit until there are two stitches left, knit 2 together
Repeat row 2 for the next 11 rows until there are only 4 stitches remaining.
Row 13: knit 2 together, knit 2 together
Bind off the remaining 2 stitches
Weave in the ends and try on your new shawl!
You can throw it over your shoulders to wear it as a shawl, wrap it around your waist to use it as a swimsuit cover-up, or fold it in half and tie it at the back of your neck to create a bandana scarf.
And did I mention that it took me less than 30 minutes to make this? Arm knitting is amazing if you're in the mood for some instant gratification.
Happy (arm) knitting!