Thanks to other members of the Cricut message board, I discovered that the Snapware Ribbon Dispenser was a perfect size for the overlays and the additional tray would hold the cartridges. However, I did not like the idea of the cartridges jiggling around all over the place. I tried several different things to hold the cartridges in place but wasn't happy with anything. I finally decided to design my own little boxes.
Of course, that led to designing dividers for the overlays and tags to identify the cartridges without taking them out of the boxes. The boxes, dividers and tags were cut with my Cricut from colored file folders. I felt that the file folders would hold up to use better than cardstock. The tags are attached to the cartridges with ribbon by removing the top screw in the back of the cartridge, tieing the ribbon to the screw and replacing it.
Here are the cut files for the boxes and dividers. The boxes file was created using George and Basic Shapes; the dividers file uses Fabulous Finds and George. The tags are cuts from each cartridge. I have them divided into 3 different files: Tag 1, Tag 2 and Tag 3. I do not have a cut for all of the cartridges. You can design your own, but this will give you an idea.
The ribbon dispenser holds approximately 35 overlays with dividers and the shorter tray holds 45 cartridges in the boxes. I've been using this system since February and have been VERY happy with it. It's now so much easier to take my Cricut supplies with me--and SO much lighter. To the left is a picture of the system all put together along with an extra tray holding Stickles, paint and some of my Cricut tools.