There are two files included here. The box and the lid. You can print them separately if you want them to be different colors, but they both fit on my bed (Ender 3v2) at the same time. 

Update

I have added a new version after feedback from him. This one has an opening on the side for him to easily grab part way through the stack and pull it up. Also, this definitely needs to be printed in PETG because the first one we printed in PLA warped while sitting in his truck.

I used Prusaslicer to slice it.

Layer: 0.2

Infill: 15% is what I used, but you could adjust if you wanted

No supports or brim needed