You almost always have to sand and use spot potty. You can also smooth the plastic with an acetone slurry made from scrap abs. Labor intensive, but that’s why the price might be $250 each.A few years ago I looked into printing in ABS, and at that time, the finish was not smooth enough due to the printing process to allow chrome to look smooth and shiny.
Things may have improved now...
A guy in Australia was "re-popping" the '67 Imp turn indicator lenses a number of years ago, but I think that party ended a while ago. Would be great if someone else found a way to do them. Even if you manage to find NOS lenses, that plastic is now 56 years old, and not as flexible as when new.......