Probably a little over-engineered, and could get away with 20-30% infill and 8 walls. Screw holes are 6 mm and access holes are 8 mm to accommodate a 1/4" Phillips bit.
 

Print Settings

• Printer brand: Bambulabs
• Printer: Bambu X1C
• Supports: Yes
• Resolution: 0.12
• Infill: 50
• Filament Brand: Bambu Labs
• Filament color: Black
• Filament material: ABS