I tried permanent marker on one of the pre-production samples. It kind of colored them. I had an old marker and only tried one coat... so a little more effort may make that method work. I think brush painting them could work as well if done right. The paint would need to be thinned properly and they would need to be placed on an absorbent surface (paper towel perhaps). The issue with brush painting them is the paint will fill the small areas between the ratlines. If the paper towel was allowed to soak up that excess paint, I think it could work.