Where I live, traffic is dense. We have a plethora of motorized vehicles in a relatively small area, from big trucks on down to scooters. We have a lot of narrow streets and alleys too. Also, here in Taiwan we enjoy a high percentage of motorcycle and scooter ownership. It used to be highest in the world, and may still be. Scooters and motorcycles are often streaming past cars, whether those cars are parked, standing, or under way. It is dangerous when a car door opens and oncoming traffic, either two- or four-wheeled, does not have enough warning.
I am particularly sensitive to this problem since a slight incident that happened a few years back. It was about 8:30 one rainy morning. I was riding my motorcycle on the way to work, and approaching a red light. Everything was a bit blurry because of the rain on my visor. Legally and in accord with local practice, I was passing to the right of the waiting cars when the right back door of one opened suddenly! The front of my cycle hit it and glanced off at an angle, but I didn't go down. A schoolgirl got out and seemed quite concerned that the car door had sustained no damage. That was annoying. What about me? Someone in the car was scolding her. But I didn't say anything and neither did she. Car door was okay, motorcycle was okay, she shut the door and walked, the light changed, and we all went our separate ways.
I've had two or three cars since then, and now I like to paint the door edges a bright, contrasting color so it is obvious to approaching traffic when a door is opening. As it happened, I painted another set of doors yesterday, and took some photos.
Step 1: What you need
1 can white spray enamel or lacquer
1 roll masking tape
1 non-orange car
(Optional) some newspapers, if you need to do more extensive masking