So after sanding with 600, no buffing is needed because the clearcoat will shine and seal the plastic? When you say mix good grade automotive clearcoat, do you mean cutting it with laquer thinner so it is sprayable?
I've done dozens and dozens of all sorts of headlights,from Audi,BMW,Honda, Ford,Toyota,depending on how the lense is designed, some lenses are clear and at night when the lights are on,if you only use 600 you may notice sandscratches, but if you finish sanding with 1000-1200 grit prior clearing,they will look as good as new,this is by far the best method that will last for years,all the other polishing stuff is only temporary
by saying mix good grade automotive clear,I mean decent clearcoat you would use painting a car, not a lawn chair,and PLEASE, I beg, STOP mixing laquer thinner in clear or in any refinishing materials, that junk is made for laquer paint and cleaning spray guns ,I wish they would just stop selling this junk, because all it is ,JUNK,
use directions on the label of the can for mixing ratio,please or ask the supplier for tech sheet