I made a hinged box that fits in the gridfinity system - specifically to fit a small screwdriver set I have. I'm sharing the empty box here, since I am assuming that will be more useful to people. It has the exact same outer dimensions as a normal 1x3 by 4 high gridfinity box, and will perfectly stack as such.
The box uses a piece of filament as the hinge - melt the ends with a heated piece of metal to ‘rivet’ the hinge pin in place. Additionally there is a version that fits a 6x2mm round magnet, simply glue it in place.
The author marked this model as their own original creation.