I used a Joann's tote bag as a model, about 14 x 18 x 6". I lined the chambray fabric from the apron with a thin layer of fleece, which gives it a nice hand.
The lining is a piece of vintage cotton, the bottom re-inforced with Timtex. I added a large zippered pocket, on one side, a smaller pocket on the other, and a gathered pocket for a water bottle.
One side has the original apron pocket:
The other side has one pocket made from the top of the apron, with a small square pocket on top of that.
The straps are made from the apron ties.
And it's done!