Like the original model, print both of these (I used PETG) and line them up with the cutout for the parcel cover's rear perch.  Line them up, drill a hole suitable for an M3 screw, insert M3 screws and nuts and tighten.  Works just like the original clips.

I used M3-0.5x20mm but those were a bit long.  M3x14mm would probably work.