Gordy & Ken, I will do my best with some answers. When I do gauge faces, I will paint the whole molded gauge face black, when dry I rub paint off the detail (numbers, dials) with a sharp toothpick and sometimes have used a pencil eraser when the gauges were large enough. I then pick out all the dials or small warning lights in the color I want with a 0000 brush. I mix a small amount of the epoxy on a file card or paper with a toothpick and flow it into the face with that. I have a small amount on the toothpick and touch the center of the dial and it will slowly flow. If you need more, just touch the same area with more epoxy. The more you do, the easier it is to judge how much epoxy each time.
There is a product out there called Rustall. Its a 4 part system and goes on like a wash which has black, rust, dead flat and some dusty-grunge powder. I usually pick it up from Micro-Mark and I think they have other systems. This one is the only one I have used and I like the results. I have a couple of rusty trucks in the Autos section of this forum, if you get time, look em up and you can see some of the results of using Rustall. I can PM you with some pics and some explanations of how I did some of the things if you want, be happy to. The way I do it is not the only way or even the best way but it is as good as any I guess. I am sure the Armor guys have some ways I don't know about. I have picked up most of my tips over the last 30+ years from others, Don Emmons, Tim Bongard, Terry Jesse just to name a very few. The credit goes to them. There are many others.
Some of the things I tried the first time didn't work but I just tried again. Keep at it and develop your own way, sometimes it works even better! Keep Glooin' guys, I like all of it!
Nothing ever fits……..and when it does, its the wrong scale.
To make mistakes is human. To blame it on someone else shows management potential.