FOSBOS is an completely free organizational system, every model is open sourced including both fusion 360 file and the step file. All the drawers are designed after the gridfinity standard.
This model is for the lid, there is really not much to say about it, print it in multiple colors if you want. Strap it all together with some super glue and slap it on the top of your FOSBOS.
Please have a look at the assembly model(here) for more information