Hi Mr Aussie,
I have done this on several sets of plastics and it takes a lot of time, as all the work is done by hand, also I am a bit anal with the result. Depending on the condition of the plastics depends on the grade of wet & dry paper. If you need to get scratches out, work on that area first, with a more course of grade. I would start with 120 or 180 if this is the case. If plastics are ok, start with 240 and sand all surfaces. Then progress to 360, then 600 and 800 to finish. This will take some hours of your time, but it should be smooth enough for the next part. You will need a car cutting compound, and use one generous application to the entire surface. Buff product off with a clean rag. The last part of the process is to apply a high quality car polish with a very fine cut in it. Meguires, or something equivilant will get a great result. Apply as required and you should have a great result. It is a bit of work, but if you can't get new plastics the effort you put in is rewarding.
