Merry Christmas, and thanks SA!
I really didn't use any special techniques for painting this project, other than using my airbrush to add the last couple of coats. I started by brush painting the entire model with flat black acrylic craft paints. Nothing special, just regular little craft paints from Walmart. Then I brushed the main bodies with a flat leaf green which is kinda bright. Brush painting these couple of layers brings out some surfaces while allowing crevasses to remain a little darker. Then I sprayed the last two coats a darker flat green. This gives yet another layer of faux detailing in nooks and crannies, and smoothes the surface down as well. When I airbrush these craft acrylics, I cut the paint with about a quarter volume of water and another quarter volume of Floetrol paint leveler/spray prep liquid I bought at Home Depot. This makes these cheaper paints flow through the bairbrush smoothly and the finished coat is smoother and thicker. A quart costs about $6 USD, and it only takes an ounce or two to mix up a small cupfull of paint. Honestly, that's it, no secrets.
I also revamped the hardware moving the control board to a hand held controller. Hopefully it will reduce weight and give myself a controller that can hold the battery pack. Here's a video: