2018-10-16: I updated the small middle boxes with a slightly smaller outline of 59,5mm x 30,0mm, according to baryluk's comment.
Replaces the front box of an Allit EuroPlus Flex 37-15 organizer (order no. 457202) with six separate boxes, which allows to take them out individually.
You'll need to print two of each size for one organizer. If you want the lid to shut tightly, you'll need to make some cuts in its separating plates, as can be seen in the last image.
Thingiverse removed the commas from the filenames, so to be clear, measured at the top, the sizes of the three boxes are
31,0 x 60,0 mm
48,5 x 48,5 mm
48,5 x 66,5 mm
Note: If you are looking to replace the actual boxes, have a look at Allit Europlus Flex Insert by Noloxs.