Project Guides and Tutorials
There are thousands of free projects and plans available on the Instructables website for just about any kind of idea, you can simply browse through their main sections or search for a specific type of project to find plans, schematics, videos, and instructions to build or modify their projects yourself.
The tabbed box is one of the simplest and most useful things to design for the laser cutter. There are several online applications that will take your input and allow you to download an .svg file that can be incorporated into Inkscape, CorelDraw, or Illustrator. In my view, using an Inkscape extension is by far the easiest way to design your box and make adjustments right in Inkscape itself.