This covers the holes in the Anet A6's frame if you have routed your cables somewhere else and have them empty.

There is a plain version and another decorated with a hexagon pattern. These print really fast and don't use a lot of material.

Print instructions

Rafts: No
Supports: No
Resolution: 0.2mm
Infill: 15%*

Notes:

*The infill doesn't really matter, as this is mostly a perimeter model and it's pretty thin. I printed at 15% and that works fine.