I recommend 3 top and bottom layers with Fast Honeycomb infill. Other infill pattern can be selected.
In the included files you can find 4 Stl files, 4 gcode file for use only on a Creality CR10 printer (300x300x400) as well as the CR10 simplify3d settings for each sol file.
Fell free to ask anything you have doubts.
Bill of materials:
-> eBay link
Only the Top file need infill on the Fan overhang