What kind of paint would I use?

Most paints will coat plastic as long as you prepare the surface well first.

Wash and dry the plastic then go over it with a rag dampened in turpentine/white spirit to remove any hidden grease.

Then, this is the most important part, the surface needs to be given 'key' meaning that the hard smooth surface of the plastic has to be very lightly scratched so the paint will adhere. The best way to do this is by rubbing it all over with steel wool or very fine wet-and-dry paper. The plastic should end up with an even matt surface that will now take paint quite well.

If it's for indoor use, it will be easiest to use regular emulsion paint like you would use on your interior walls. But, emulsion paints will flake off outside as they are not good with moisture and cold. For outside use you will need an exterior undercoat and top coat (just as if you were painting your front door). Aerosol cans of paint, like those used to touch-up car paint work will work well too.

Providing good key is the most important thing.

If you go to a store with a large selection, you find spray paints made specifically for plastic, they say it right on the can and work great.

Krylon, and fine.