My mom's C3 Pluriel used this part to keep the trunk closed and the roof attached. Citroën used a plastic piece for this, that they discontinued. A secondhand piece was more expensive than a 3D printer, so this was the perfect excuse to finally buy one.
I don't have any pictures of it installed, but it fits
For structural reasons i printed in 100% infill, also don't print this is in PLA we ended up selling the car to the scumbag asking 3D printer prices for this piece. If this is meant as a permanent fix i would suggest 100% infill on PC or any other real strong plastic.
Update: I have uploaded a mirrored version for the other side and named them to the according side of the car.
The author hasn't provided the model origin yet.