No pic, yes, you need an airbrush or a paint gun.
I used HOK lime gold (KBC02) HOK black (BC25) and a HOK Orion Silver (BC02)
I used a mix of 60% lime gold, 30% black, 10% silver (more or less). You could make it more green by adding a little bit of blue in.
Painting with an airbrush if it isn't candy is easy and it's not too expensive. The paint costs more than a can of spraypaint (and multiply that when you use muliple colors) but it last alot longer. My airbrush compressor was $35 on sale (normally $50) from harbor freight and i'm actually currently using a $5 airbrush. It actually works better than my "nicer" one as it has one adjustment so it's easy to get it to spray wide (but would be awful for art).
The major downside is the cost to start. I spent around $90 to do my valve cover the first time. That would be for the compressor, cheapo airbrush, paint and reducer (i had to buy a full quart) But, i use maybe 1/3 of my paint and my reducer will last me years. If you would be using spray paint alot, this intial cost makes up for it. Plus, the results are much better. On top of that, it's alot less work as you need to wetsand spray paint like crazy to get it looking good, where with this, after primer, i don't wetsand until the last coat of clear (that saves me probably 3-5 wetsanding jobs compared to spray paint).
My point is, even though it's expensive at the start, it will make up for it over time, with better results. Oh, and you can use almost any color in the world, or mix your own.
Lastly, you can use much cheaper paint too. Oil based rustolium looks as good as spraypaint or better, is $3-4 for a 1/2 pint and you can use normal paint thinner. You could do your valve cover for $10 in paint and that material will last you years. Plus, you can mix up custom colors.
Sorry, retardedly long post, i just feel like this has been one of the better investments i've made in price (it will have almost paid for itself after i do my wheels), quality, and time spent and i can't remember the last time i used spray paint, outside of primer and clear, which will soon change.