Wanted to put our house number on a plastic trash container.
Put craters in the surface outlining each digit with a soldering iron and cleaned them up with a countersink.
Last step was to put a drop of contrasting paint from a finishing nail into each pit. Easy, right?
Well, the paint consistently jumped 3" off the nail and made a radiating spray pattern onto the surface, I guess due to static charge.
Plan B is to drill through-holes, plan C is to put tape inside to give the hole bottoms a contrasting color.