If you plan on going full show with your truck, chances are you'll want to bring the color of the exterior into the cab. In a lot of older trucks, this is no sweat because most of the interior panels and dashes are made of smooth sheetmetal that doesn't require much work to paint. On the other hand, newer trucks have a lot of textured plastics that aren't so easy to work with.
The main problems associated with painting interior plastics are the rough surfaces and the prep work required to adhere materials to them. If you're planning on taking the trouble to pull out these pieces, then it's in your best interest to take your time and do it right. Smoothing them will bring out the optimum shine, and a thorough cleaning during the process will extend the longevity of the paint. To help you get a better understanding of the procedure, we had the pros at Kustom Werx Autobody show us how they get the job done.
What's in the toolbox?
Sandpaper is used throughout the stages, and here we have 180-, 400-, 1,500-, and 2,500-grit along with a Dura-Block sanding tool. Also needed is a degreaser, an adhesion promoter like Bulldog, high-build primer, and a primer sealer to go on before the paint.
PART ONE: PREP IT!
1.As you can see, our hard-plastic glovebox cover has a lot of texture to it. Smoothing it will help in prepping it and give a nice overall look when painted. | 
2a.Justin used a sponge to apply the wax and grease remover over the surface of our piece. | 
2b.It is highly suggested that all pieces get a full coat of the cleaner, and this applies to all the crevices as well. After the application, he simply wipes the cleaner off with a different clean rag or paper towel |
3a.Next, he used a dual-action (D/A) sander with 180-grit sandpaper to remove the texture. If you're familiar with a D/A, it will help speed up the sanding process. | 
3b.If you don't have one or you lack experience with this tool, you could use a sanding block like this Dura-Block. When sanding with the block, Justin works it up and down, side to side, and then in crisscross diagonal motions. | 
4.The D/A or sanding block will work on all flat surfaces, but for areas like this you have to hand-sand with the same 180-grit paper. The key to a nice painted look here is to make sure all of the texture is gone from the plastic. If areas like this are missed during the sanding process, the overall job will look bad. |