I filled in the lettering with the some nail polish. Make sure the letters are totally covered. It's okay to go outside the lines.
Once it's dried sand the top down until it's smooth and the nail polish is only left inside the letters. Also helps to create the looks of an eraser by rounding the corners a bit with some sand paper.
Then I sprayed a matte clear coat over it to seal it.
The author marked this model as their own original creation.