This is my version of a puzzle sort box, which is stackable and has a lid for the top box. Created with FreeCad to get the shape right and the cornering as it should. 

You can edit this version anyway you want, I would suggest doing this within your slicer and make sure to use the Percentage.

The top lid, can be printed as completely flat, or as I have created with some shuriken puzzle pieces I found, link to this can be found: 

https://www.printables.com/model/356038-shuriken-puzzle-piece-tessellation/remixes