Here I is! I had my shop do it. I don't know the EXACT procedure, but I know it entails some filling in because the piece is heavily textured, then some sanding to smooth it out. I don't know what it was filled with, though. Anyone with any kind of experience could probably guess it easily if you're paying someone else to fabricate it. After sanding, you'll want to have clear bra put over it after the paint has either had time to cure properly or just dried completely, depending on paint used.
Here's basically what it looked like when I first got it done.
https://farm8.staticflickr.com/7402/...a2c7498b_h.jpg
https://farm6.staticflickr.com/5574/...3f51cc96_h.jpg
When it was first done they just painted it with whatever they had at the time and told me to bring it back in a week after the paint cured. No clear bra was applied at the time for that reason. Well, in Anchorage, Alaska, they lay down gravel on the roads instead of salt, so my front was dinged up. They never actually got around to applying the clear bra or touching up the paint, so here's what it looked like during the middle of summer (kind of hard to tell, you'll need to blow it up a little).
https://farm4.staticflickr.com/3857/...7f3364c6_h.jpg
Those little white splotches are dings in the bumper. Eventually they took the car back and got it professionally painted, where it dried in a day, then had clear bra put on it. That was maybe 5 months ago now and the bumper still looks brand new. Actually my entire front looks new because I had clear bra applied right after I bought the car and they replaced the clear bra, so the paint is untouched. I don't have a current picture of the front, but it looks the same anyways.
I don't know how much it would cost to have it done since mine was done for free. My shop takes REALLY good care of me and I'm super appreciative of their kindness. I show it by continuing to bring them business!
Anyways, if there's anything specific you want me to ask them about the procedure, let me know. A member on here pointed out that it mostly works on my car because it's already black. Honestly, I was going for a lighter black, more of that duller, yet glossy dark gray that the BRZ STI Concept uses. I think if you could get it closer to this instead of the deep black like I have, you'd be golden!
http://www.autotribute.com/wp-conten...cept-front.jpg