I recently noticed an Incredible Hulk toy that was released for the new Hulk movie. This toy came with a Hummer which was about the right size for GI Joes. I figured a modern-day Cobra organization would be using these things, so I picked one up. I also grabbed a can of Krylon Fusion spray paint for plastics and bought some decals from Cobra Stickers.
I removed all the stickers from the Humvee, then took it apart. I spray painted the pieces separately so as to be able to get every nook and cranny. There were some designed that were painted onto the truck that the spray paint had trouble adhering to, but the paint eventually covered it after using several coats (with drying in between).
It’s nothing fancy — I just wanted an overall “Cobra” color scheme — but I think it looks okay:
Before:
After:
There was also a “button”, of sorts, that stuck out of the front grill. When this button was pushed in, it would smash the hood (i.e. “hulk smashing action!”). I removed this button and super-glued the two halves of the hood together to give them more stability. A more serious customizer would probably want to putty up the crack between the two halves of the hood before painting it.
The cannon also fires a plastic missile an impressive distance.
Also, the Krylon Fusion paint actually melts the plastic, fusing the paint into the plastic itself. If you’re thinking of using this stuff, you have to be careful when handling freshly painted plastic as its surface is quite deformable while the paint is still wet.
I had the rear trailer hitch piece sitting on the ground, with the bulk of the weight of the piece resting on a painted surface and the plastic edge there flattened out a bit. If your not careful with this stuff, you can easily end up with fingerprints melted into your plastic parts.
Because of this “fusion” action, you’ll want to wait until the paint is nice and dry (at *least* 24 hours) before putting figures in it or you’ll risk melting them a bit.
The Amazing World of Don Dueck 
