Updated to version 1.1
Option to add support blocks in corner of box for when the dividers don't support inserts or you want a full open base. This option is in the compartment section of the parameters.
NEW Custom divider layout - see section below.
New helper Excel file to allow you to process layouts.
This is an updated version of the basic box https://www.thingiverse.com/thing:3503304 that allows for dividers in the box and inserts that you can put inside as well. The box can be made to custom size and any number of dividers in each direction.
The parameters are documented in the design but if you have any issues let me know. I find a lid tolerance of 0.4 and insert tolerance of 0.8 gives a good fit but try out a small version to test before printing a full size one.
The parameters comp_perc and insert_perc are percentages of the inner depth so you can split it evenly as 50 and 50 or have box dividers at 40 and 2 inserts each at 30 depth. Any combination you like as long as it all adds up to 100 or less.
Custom divider layouts
You can now have custom divider layout. In the Box and Insert Custom Divider Layouts section you can define a vector like [1,0,0,1,0,1,1,0] for both x and y direction on the box and insert.
How it works
Consider a box with 3 x 2 compartments which gives 6 compartments in total. This has 1 divider in the across direction and 2 dividers upward. The across divider is split by the upwards dividers into 3 pieces and similarly the upwards 2 dividers are split into 4 by the one coming across. So we have 3 dividers in x direction and 4 in y (2 lots of 2).
So starting from the bottom left and work across and then up for x and up and then across for y we can say that the dividers are x [1,1,1] and y [1,1,1,1] when 1 shows they are filled in. So if we change that to x [1,1,1] y [1,1,1,0] we would remove the last upward divider so that compartment will now be 2 compartments wide. See the picture description for further details.
The included Excel file can be used to generate the vectors needed based on your layout. It's a macro based spreadsheet so you'll need to enable macros to run it.