I really like the model by “Matt C" but I didn't want there to be any way material from one box could fall into the next one over through the connectors. I also didn't want to have tabs sticking out on the exterior edges that weren't being connected to the next box over so I remixed them into these ones and added friction fit lids. They are parameterized and I have included the Fusion360 file for you to play with should you wish specific dimensions.

They are made to be printed vase mode with a 0.6mm line width. They should work in normal mode as well so long as you have a 0.6mm line width. Any other line width and the tolerances probably won't work. If you find the connectors too tight or too loose I suggest scaling the x and y directions a bit leaving the z direction alone. The current stl for the connectors has a nice friction fit when printing on my prusa mini.

Enjoy