We have allocated parking spaces at home and have a Freelander parked next to us which I identified as the cause of numerous door impact dents on our previous Jazz and Civic before that. Keen to avoid them on the new one I bought a
https://doordefender.net/ which has completely solved the issue. Expensive, but brilliant.
Today however I managed to trap the plastic ball in between the two sections of the defender against the B pillar and, fairly gently I think, closed the door on it. The door didn’t close properly, but the door edge ended up bulged outwards right in the middle of the sculpted swooping curve along the side of the car. Not a lot, but I knew I was there, so applied some gentle panel beating and got it back into shape almost perfectly thankfully.
The point of the post is that I dread to think what something like a seatbelt buckle or similar would do if a small piece of plastic, which should be deformable not hard to be honest, can deform the door!
I will be a lot more careful in future.