This is called a project bag because lots of knitters/crocheters use it to carry their small projects in. It's easy and fun to make. I've used this pattern, the instructions are clear and the bag turns out very well. I would imagine that the pattern can even been made larger if the size shown is too small for your needs.

Have fun. Enjoy!!

http://needled.files.wordpress.com/2009/03/tk.pdf