These boxes measure about 100mm (L) x 60mm (W) x 35mm (H). The lid has a bump that runs along the inner lip securing it to the main box with the corresponding notch that runs along its outer lip. There is an indentation just below where the lid meets the box to allow for easier removal of the lid. The lid is also designed to bend slightly to allow for easier closure and removal. I designed a few versions with 6 compartments, 4, and 1 large compartment. I'm able to print this at 0.2mm at 60mm/s and have a secure closure. Very thin, small washers may squeeze through the gap between the top of the compartment divider and the lid though.
Hope you find it useful!
UPDATE MAY 9, 2015
Just added an 8-compartment box. Wow I didn't think this box would get so popular. I'm glad you guys like it!
UPDATE JULY 30,2019
Added a couple of shorter variations. I found that the old boxes were just too deep and I kept needing needle nose pliers to get at the stuff inside.