When I designed this box, I wanted a very nice high quality box. I wanted it to snap close nicely without using magnets. I also wanted the hinge mechanism to have a nice crisp and clean look when the box was closed or open. 

SMALL BOX Outside dimensions are L = 3.031" D = 2.062" H = 1.250" and the inside dimensions are L = 2.812" D = 1.625" H = .900" 

MEDIUM BOX Outside dimensions are L = 4.050" D = 2.750" H = 1.670" and the inside dimensions are L = 3.750" D = 2.175" H =1.150"

LARGE BOX Outside dimensions are L = 5.050" D = 3.450" H = 2.090" and the inside dimensions are L = 4.680" D = 2.730" H = 1.450"

  I used a piece of filament for the hinge pin. When you install the filament it is best to round one end with fine sandpaper and leave the other end long to give you something to hold onto when installing. You first should twist and push it through each piece separately to make sure the holes are clean of any debris or obstruction in the holes. After you are sure the filament will go through the holes, assemble the box and then twist the box and filament at the same time making sure you hold the filament close to the box so it will not kink while you are pushing it through. This can be a little tricky. Then use a razor blade or sharp knife to trim the end off. You don't even have to cut it all the way through, just cut it half way and break it off. The first few times you open and close it it will be stiff but after that it will be nice. I have never tried using any other type of filament other than Bambu PLA Basic. Keep an eye out on my designs because I plan on making several other size boxes. And please let me know if you have any Ideas for me to improve my designs.