The author remixed this model.
I had a very different need and was just searching for a latch when I found these boxes.
I needed to attach some flags to a 1 inch square post for a parade.
I used this design by shrinking it so the inside dimensions were 1 inch deep and one inch high and a little over one inch wide. I then used the extrude feature in Fusion to extrude cut and cut the ends off. That left me with a 1x1x1 collar.
I extruded the top and bottom and put holes in them for the flags to stick into. Rather than make a support for the latch I just extruded the the very edge down to the print surface. I made it thin enough that it was solid and I was able to snap it off. They worked great.
I want to make sure I credit Windrose as the true creator. I just did a little mod.