Welcome to Project Box.  There are all sorts of parametric designs out there for people who are fluent in CAD, but what about the average person? Maybe someone like me, who is just happy using TinkerCAD?  That is who Project Box is for. 

The basic box is designed in three parts and made to be about as simple as possible. The front latch folds in flush with the box design so that it can be used as a label as well. There are a couple of trays included for inserts to make the box design more usable, but the point of this is modularity. In the downloads, you will find several zip files. These are pieces that you can snap together in apps like TinkerCAD to assemble your own box with any dimensions you desire. 

All the corner pieces should be left in the specified dimensions, but the connecting centerpieces can be stretched as far as you like. I highly recommend watching the video so you can see exactly what I mean by this. I'll admit it's not as elegant a design as something you could do in Fusion or other CAD programs.  But again, this is designed for regular people like us.