I'm planning on spraying an upper, lower and FF handguard with Duracoat aerosol this weekend.  The upper and lower and related masking seems straight forward.  My concern is spraying the handguard.  I want to be able to get good coverage into all the nooks and crannies, so do you just use multiple light coats, heat flashing in between to get good coverage into all of these holes?  Also, do you spray down into the end of the handguard, or just mask off the inside so it stays a crisp black line?  Color will be Duracoat's Midnight Bronze.  Here is one of my other builds that uses the same handguard:

OK so a follow-up to my own questions.  For future reference of others, I used Duracoat Aerosol in Midnight Bronze.  I cleaned all the parts with an initial wipe of alcohol and a paper towel.  I then sprayed the parts with the included spray and wiped it down again.  The included cleaning spray evaporates very quickly.  I gave it all a quick blast with the air compressor in an effort to remove any remaining lint.  I hung all the parts on some solid copper wire, and gave them all one more shot with the cleaning spray.  I sprayed 4 light coats on each part, flashing it off with a hair dryer on high between each coat, approximately 1 minute of drying.

Coverage into the end of the handguard was good.  I did not need to mask off anything.  I'm not sure how it would be with a lighter color, but dark colors blend in well.  I ended up with a couple of very small runs on the lower receiver near the roll marks.  Everything else looked perfect.  I waited 1 hour to let it set, then hit the runs with some 400 grit sandpaper (lightly), then touched it up with a Scotchbrite pad.  A good cleaning on that area once again, two light coats of Duracoat with flashing in between, and one final coat over the entire lower receiver.  Looks just like the rest of the parts now.  

Overall, I'm very pleased with how it looks, though the color did come out a bit darker than I had hoped.  It does look much better in direct sunlight, as most paints do.  The flake really pops in the sun.  I'm hoping to do final assembly this weekend, but I couldn't resist a partial assembly to get a feel for the overall look.

https://youtu.be/pkW8zVEUbiA

Final construction complete, here's some outdoor photos in the sun.

Very nice!  Thanks for the write up, as I am planning on using the same type of finish for one of my builds.

Hope it helps.  Let me know how yours turns out!

A couple more pics and one for comparison to standard black.

quite the collection, i like how it turned out, the bronze color is classy.