i've scratch the plastic to deep

The best way is to use progressively finer grits of sandpaper and the scratches will eventually get sanded out. Of course you will lose some surface detail at the same time.

If all else fails, give Mr. Surfacer 500 or 1000 a shot. It's basically very thin putty. simply paint it on to the scratch, and gently sand the excess off. You might need to do a second or third application to bring the stuff level with the surrounding plastic.

Next time, not so much pressure. Save the elbow grease when cleaning the range.

if its a fine scratch but deep, sometimes just plain old floquil primer will fill it after about 2 or 3 coats, then wet sand it. this has worked for me on ocassion.

another way i fill cracks sometimes is (and this is not a practice that has been posted around here anywhere but it has worked for me a time or 2) to sand up some plastic dust so that it fills the crack you are after, then, take some Tenax-7 and touch a little to the crack and it will "weld" the dust in place. do this a couple of times then sand with fine sand paper. i've got this to work on occasion. later.

Thank you, guys! infact I just talked to my hobby shop, and they ask me to do the same, some overcoat of primer. may god help me

I used Mr. Surfacer on a ship's hull that was torn up by a sanding drum on my Dremel. I applied this stuff and sanded it down, and you cannot tell it was ever damaged! Great stuff!

i've always wanted to try mr. surfacer but i cant read the bottle and wasnt sure how to. thanks duke for the heads up. later.