I used the 12x12 mat, Fit To Page and Blackout Features to cut my card stock base. The Cricut will cut this out at 8 3/4". Once it is cut I score, fold, and ink the edges of the box.
Here is what the card stock looks like cut out. I inked the edges. There is small oval that will fit on the flap if you choose to decorate the flap.
The mini notebook I made is 5 1/2 x 4 1/4. I use the bind it all and the small wires to put the notebook together with about 30 pages.