A little tech tip. I had an 2007 Subaru sti. And made a cold air intake for it. I used a red wrinkle finish paint to match the factory intake. I used a heat gun to speed up the drying and wrinkle process and it worked great. The pieces I used the heat gun on actually came out better. Don't go at it heavy with the heat or you will mess the paint up, just ease into it. You will actually see it wrinkle right before your eyes and then work your way around the part. I discovered This from painting in the garage in the winter before I put heat in. It was too cold to paint. So that's were the heat gun came into play.
Necessity is the mother of invention.
The valve cover looks great by the way.
Good luck
Rich.