Cacuun mentioned using a container for knitting with two balls of yarn. Some time ago I came up with this idea and it's been very helpful -
I take a gallon zip loc bag and using a zig-zag stitch I stitch down the middle of the bag. This gives me two pockets for yarn and I can either clip the corners and pull the yarn out through the bottom or, if I'm using one without the little zipper thingy for closing it, I can pull the yarn out the top corners and just squeeze the top shut along the tracks in the middle.
This was so helpful to me. All I had to do was just flip the whole bag over and if I flipped it the wrong way, just another couple of flicks of the wrist and I was good to go!
Hope this helps!