Anyone experienced enough to try this technique is probably experienced enough to realize the importance of knitting a swatch. So, there isn't much that needs to be said on this topic.
Aside from figuring out how you want to carry the yarns, learning the rhythm of the changes, and determining gauge, working a swatch allows experimentation with various methods of casting off.
On my swatch, I bound off in several techniques using a colorful, contrasting yarn so it would be very easy to see exactly what was happening. Ultimately, I chose to graft the two sides together. It made a lovely finish which is neat and elastic. It required patience, but so did the rest of the double knitting.
I live in Berkeley, California, and have been knitting and crocheting since I was a little girl. I rarely knit from patterns and love the challenge of knitting something that looks simple but has hidden touches only other experienced knitters see. The same applies to the work I do on my knitting machines.
I try to incorporate techniques in hand-worked projects that don't lend themselves to machine knitting equipment intended for home use. This two-color, textured work is just such a technique.
Emily Lynne Wilcox, Berkeley