The challenge of the notion to use one’s arms as knitting needles is, lacking a third hand, how to ‘throw’ the yarn. After a bit of experimenting the following works:
Cast yarn onto left forearm, say, six stitches using the simple loop cast on. Put right hand through st # 6 (the last one cast on and nearest to wrist), reach down and grab the yarn hanging from the sixth stitch, pull yarn back up through that stitch and slip resulting loop onto right forearm. Repeat across row.
Now all six stitches are on right forearm. You can transfer these stitches
back onto left forearm – you have to reverse the order to get hanging yarn back at front. I find it easier to just knit back across the row from right to left using left hand to reach through the first stitch (nearest wrist on right arm), pick up the dangling yarn, pull through stitch, put loop onto left forearm etc.
Experiment with different fibres, different thicknesses of yarn. I’ve made a scarf/necklet using purple hemp yarn, towels using ripped strips of flannelette (from the fluffy edges of an old bedsheet), played around using men’s ties as the yarn (I have a large collection) thinking to make a vest.
Knitting Intuitively With Almost Anything will be available on Google Books soon and Arm Knitting is in it.