customizing interior parts, color

It varies a lot but there are several techniques. My personal favorites are to use either water-born paint, or to use a flexible paint such as "fusion" or vinyl paint.

You can also use films over your existing parts but getting an exact match to your exterior is hard-to-find most of the time.

Another way is to get a custom color match with epoxy paints designed for use on plastics and rubber. I'm not too familiar with these but if you get someone who knows their paint, they can mix something that can work.

Then there are the reproduction sets. If you have access to a plastics or die company, you can have your parts remade with color matched plastics and resins. However this gets pricey very quickly.

There are other options but none come to my mind at this moment.

80 grit?   i would probly start with 100  and then tapper off to 400   even more so if your wanting a glossy finish, since a glossy.

you definately want to start with at least 100 grit, then taper to probably 600 grit if you want a glossy look as the smoother the plastic, the glossier it will appear. if you only do 80 grit it will be a chewed up scratchy mess man.  then use a plastic paint adhesion promoter and spray that on then a body filler/primer spray, then sand to 800 grit, then paint a few light coats so it doesnt look runny or blotchy, then few thin coats of clear. let it dry a coupl days then put back in ur car. thats will give you the best results for a diy project.  but make sure for whatever paint products you chose to READ the back of the can, everything out there is different. hope this helps.

and post pics, we all like pics

typo

I redid the majority of my interior with a combination of Duplicolor Adhesion Promoter, colour matched paint and clear coat.

Clean your parts with alcohol, make sure they are completely dry, spray with 2 coats of adhesion promoter, then 3-4 coats of colour, and 3-4 coats of clear. No sanding needed.