Things I learned about painting/trimming a clear RC body for the first time:
I. Take your time ... Remind yourself that you just dropped $50 worth of coin on a piece of plastic and paint to make it your own. Rushing any process is your worst enemy.
II. Prep ... Washing the molding agent off does make a huge difference. If you rush this step, painting isn't enjoyable. I used a paper towel and dishwashing soap and rinsed thoroughly. After you rinse, go drink a beer (or a Red Bull for you young guys). If you're going to paint before you trim, the lexan has to be dry and free of dust. I used an air compressor to get dust out of the inside. You'd be surprised how much lint/dust other fine particles settle inside the body as it dries.
III. Trimming ... Invest in a pair of lexan scissors; two pairs if you can swing it. One straight and a curved pair. I found this step to be the most monotonous and frustrating. It's boring and time consuming. Start away from the trim lines and work your way in. If you over cut the trim lines becuase you started cutting to close ... well ... you know the rest.
IV. Fit the body... before you paint, marking the holes where the posts go with a sharpie. NOTE: On the Slash 4x4, the rear body posts tend to "lean forward" with use. They should straight point up and down. The plastic is flexible enough to where you can bend them slights back to their original points. When the body drops onto the posts, they can/will adjust back to where they originally were. See this thread for further info.
IV. Masking ... This step makes all the difference in the world in how the truck looks in the end. I did very little in the way of design, but that doesn't mean it didn't take awhile. Things like rounding off the edges of the tape where the roll bars meet the body are time consuming but worth it in terms of realism. TIP: Using the rounded end of a small hobby paint brush helps push down the mask into the roll bars and other curved spaces. This is also one of the only steps that you can correct easily if you mess it up the first time. TIP: Once masked, hold up the body to a light to find areas where you failed to mask. Doing so allows you to catch overspray problems before you paint. You'd be surprised how many places you find that you thought were masked off, but weren't.
V. Painting ... Painting in a warm, well-venilated room helps the process considerably. A cold can of paint doesn't flow as well as one that is room temperature. If you must paint where it's cold, run warm water over the can of paint and/or leave inside the house the day before you spray. This goes without saying, but shake the can often before and in between coats. NOTE: Several lights coats are far better than two heavy coats. This takes discipline. Why? Because when you throw paint on a clear body for the first time, it starts looking cool. We get excited. STOP. ... go drink another beer and let the first coat tack up and dry. Yes, blow dryers speed up the process. If you choose to go this route, it's important to keep the air flowing through the underside of the body. Holding a dryer in place on high heat for too long allows the plastic to warp or the paint to run. I used Pactra lacquer RC paint and found each coat to dry within 15 minutes. (Again, this is a perfect time to drink another beer).
VI. Drilling holes for body posts and number plates (if your body comes with them) ... I used a drill because I didn't have a body reamer. TIP: Use a small drill bit first, then a larger one for better results. IMPORTANT: Drill on low settings. High speed will cause the bit to slide all over the place. Again, slow and steady. Once the hole has been drilled with the smallest bit, start the larger bit on low, then increase speed. I cut the holes with the protective cover still on the outside of the body just in case the bit slid and and wanted to scratch the surface.
VII. Smoothing trimmed edges and fitting ... A dremel with a medium grit sand wheel works wonders on low to medium speed. NOTE: Hold the body close to where you will trim to prevent flexing in the lexan. Holding the other side of the body and trimming a wheel well for proper fit often results in the lexan vibrating uncontrollably. TIP: Make slow, steady passes with the sanding wheel using light pressure and don't sand in one place for too long. Doing so causes friction, which causes heat, which cause warping. ... time for another beer.
VIII. Applying decals ... This part is fun and the most subjective part of the process. Stickers go where you want them. Browse the forums, search for ideas and take your time. NOTE: Drinking beer during this process effects the final results/placement of the decals. I recommend switching to water at this point. TIP: Once decals are applied, I use a paper towel to rub over the stickers, making sure that all edges are pressed down firmly.
The web is full of better ways to trim, mask and paint a lexan body, but it's also full of worse ways to do it as well. I'm simply sharing my experience with others that may be thinking about tackling this project for the first time. At the end of the day, this is a hobby that exists for pure entertainment purposes. Keep that in mind when you get frustrated.
A few pics: