I had those hex nuts loosely laying around in a box in my workshop, always was searching for the right one. So I made a small organizer with description for each nut. The organizer holds 12 round hex nuts as well as 7 hex bits.

I included the OpenSCAD model so you can modify it to suit your own needs, just change the two tables on the top of the file:

nutHoles = [ [[10, 20], 12.25, "4.0"], [[23, 20], 12.25, "4.5"], [[36, 20], 12.25, "5.0"], [[49, 20], 12.25, "5.5"], [[62, 20], 12.25, "6"], [[75, 20], 12.25, "7"], [[88, 20], 12.25, "8"], [[10, 45], 13.75, "9"], [[27, 45], 14.5, "10"], [[46, 45], 16.5, "11"], [[66, 45], 16.5, "12"], [[86, 45], 17.5, "13"] ]; hexHoles = [ [[10, 70], "5"], [[20, 70], "6"], [[31, 70], "7"], [[43, 70], "8"], [[56.5, 70], "9"], [[69.5, 70], "10"], [[84.5, 70], "11"] ];

These two blocks describe the location, size and lettering of each hole. You can even modify this to hold your whole collection of hex bits if you need to.

Printing parameters:

• PLA, ABS
• 0.3 mm layer height
• 25 % infill
• filament change at layer 33 if you want colored lettering
• 0.3 mm minimum wall line width (for the lettering to slice correctly)