Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:3943147.

An divided A3 box, nothing more.

EDIT: After printing and test fitting the boxes i found that the devider could be a little higher so that it's harder for the parts in the two compartments to flip over in the wrong side. Made a quick adjustment and uploaded it as it's own thing ( I also added the pins/feet from the original to make things more convenient).