Using two needles, this method lets you work both the front and the back at the same time so that the result is a tube.
You can see how it is a tube here: it would have been even clearer had I thought to take a photo of the completed item which was a soap scrubbie with a bar of soap inside.
How to: Cast on even number of stitches.
Knit 1, *bring yarn to front of work (yfwd), sl next stitch purlwise, take yarn to back of work (ybwd), knit 1 repeat from * to end of row
Repeat this row.
If you simply cast off in the usual way when the desired length is reached you will have an enclosed tube which would be fine for a belt or a tie, but for something like a soap holder or eyeglass case or cell phone cover or cowl you need to put the front stitches on one needle and the back stitches on another needle and cast off separately.
This is a glass case double knit in my rustic handspun.
A small pouch/necklet.
Cell phone coat.
You could make a carrying case for an umbrella or a musical recorder, a draught dodger for the bottom of a windy door, vase cover ……
Once I saw an article on a woman who knit one sock inside another using this method (or variation of same) and would impress people by pulling a completed sock from the innards of another one. I was impressed reading about it!
If you know of that article tell me where you saw it – maybe I can link to it. It was in a magazine.