My first box was fairly simple in comarison to the box I'm working on now. There were certainly fewer parts to cut out. This box will be basically the same, but it will be about 2 1/2" longer and the sides will be taller to accomodate a second tray. Most boxes made with a removable tray are jewelry boxes and don't have the dividers in the bottom, but mine will not be for jewelry, and there will be dividers in the bottom as well as the top tray.
The two most important things about box making and bookbinding that I would not have expected: math/formulas and labeling the pieces. But the paper and the process are the most fun parts. :)