My 2nd practical model. Designed in Blender, printed by Creality K1 SE in Sunlu Sunny Orange PLA+, used by me. 

The slot is 18mm wide and slightly wider than my 16" MacBook Pro. I made it wider because I was unsure about shrinkage and didn't to risk of it being too tight or not fit and lose the time/filament.

Printed with 3 walls, 15% infill and tree supports, it took quite some time to print (~6.5 hrs) on my Creality K1 SE

The supports were relatively simple to remove but some had to be sniped / cut using the Creality filament cutters and teased out of some of the hexagonal holes.