It’s all paint. I used an oil based enamel (Rust-Oleum, gloss).
I rubbed wood glue into all the cut edges of the MDF to seal them up (took about 3 coats of wood glue) and sanded it smooth. Then I mixed a 50/50 solution of wood glue and water and coated the entire cab with a foam brush ( also 3 coats followed by sanding with 220 grit). Then I used KILZ oil-based primer and shot 2 coats with my HVLP gun (followed by sanding with 220 grit). I then shot the black (5 coats) of gloss black with HVLP (thinned with VM&P Napthala). Sanded in between coats. Once the gloss black had completely dried and cured, I taped it off and used a 4″ wide smooth foam roller to roll on the paint for the stripes.
Sealing up the MDF is a tedious, time consuming process. I can see why manufacturers just glue vinyl type skins over it instead of painting, but I prefer the look of paint. I started with sealing the cut edges first with undiluted wood glue. That’ll help prevent the open grain of the MDF from sucking up your primer and paint and adds a higher level of protection. I didn’t want to use T-molding as I wanted my edges to be gloss black like the sides of the MDF. Sanding it all down is time consuming, but worth it.
I also used BONDO for hiding all my seams and joints. Lots of sanding time there as well, but it all looks uniform. I had countersunk my screw holes and then used BONDO over the top so you can’t see where any screws are.
Best advice: Take your time and don’t rush yourself. If you want it to look great, don’t settle for “good enough.” Any slight blemish that wasn’t sanded out or filled correctly will stick out like a sore thumb with gloss paint.