I have double metal front doors. Each door had 3 big plastic type decorative squares attached to them (very 80s!). I removed the squares and planned on sanding and painting the doors. Each square has now left 12 holes in the metal door (they were attached by pegs inserted into the door). So each door now has 36 small holes in it. Is there anything I can do to fill these holes that can then be sanded and painted? Any other suggestions? I am trying to avoid having to buy a new front door!

You should be able to find a metal filler in the local hardware store. One the small hole is filled you can use a little Bondo scratch and dent that comes in a small tube from your local hardware store, sand and wet sand. Make sure the hole is deburred before filling, otherwise that little crater will take forever to remove. Or take a look at your local boat store and see what they have. Prime and paint with a Rustoleum Laquer. You will have issues with expansion, so that's the reason to use a product designed specifically to work with metal.

Last summer I painted a screen door for the second time in many many years and it held up remarkably well. Painting is an art to avoid drips, etc. Cans of paint are expensive.

I drilled the wrong side of a case once for feet, so I just put screws that went nowhere in the top. You could put rivets in the holes. Rivets that go nowhere. You can get them in white or aluminum.

Liquid steel or liquid aluminum, let it dry and then sand. Then prime and paint. Another thing, how large are the holes?

The holes are about 5/16"

Yes, the posting before I made will work, just apply and sand lightly, then prime and paint.