I've had this pattern for awhile and decided to do one after doing the Bow Tucks. The pattern is very much like the Bow Tucks, even down to how the pockets are done.
The black part is a complete bag in itself, just plain black, and the colored bottom is a cover, or sleeve, that goes over the bag and elastic loops go over the buttons to hold it on.
This cover is reversible. One side of the reversible cover can be done from a fat quarter... a world of possibilities for different looks for the bag from my FQ stash. :)