I can’t see a picture either. But that won’t stop me from guessing!
You could try a decoration, like small silk flowers. A more serious suggestion is to buy used door cards that match your car and are set up for power windows. The serious suggestion is more expensive, of course.
At the risk of seeming impertinent, I have to ask the following:
Since this car is a minimum of 21 years old and has a negligible book value, how much are you willing to spend on its aesthetic aspects?
IMHO, you should just do whatever pleases you (and that is very cheap), given the incredibly low book value of this old car.
On those few occasions I helped friends do a power window retrofit, we would simply mount the window switch in the aforementioned hole. Of course back then, the switches were nice big bulky chrome bezel types which needed a good 1 1/2" square hole.
Just go to a fabric store and find something close that you can glue over the hole. You could even put one of those round red reflectors like used on trailers and it would be a nighttime safety feature when doors are open.
I think what I"d do in that situation is take a photo with me to a fabric/hobbyist home sewing type store – you now where folks typically go if the like to make their own clothes and home stuff like that as a diy’er – and see if someone there has an idea. The main downside to this, my local version of that store has a lot of cranky people working there. They don’t seem to want to be asked questions about cars and the like. If you want to know about where they keep the sewing machine needles and patterns, no problem … lol … .
Duct tape comes in colors and patterns. You can put a long strip across the door panel and you can do it again when that pattern stops looking so good to you. One of a kind.