RC Painting

There are many ways to approach this, but these are my recommendations.

You should paint the parts after test fitting them and before strap assembly. It is not usually necessary, but you could clean the parts to remove finger oils before painting.

Spray Painting

The RTP helmet and seamed kits come primed in gray. I would recommend your first coat to be primer close to your base color. White usually takes multiple coats, which you can apply with primer only or with flat/matte white paint for follow-up layers. Read your paint instructions closely. Rustoleum paints work great for these, but I am sure many other brands will work. Your base coat does not need to be completely solid for a white base. Commandos are not pure white and have a lot of weathering, so usually 2 or 3 coats are fine. But the more layers you have the safer it will be to sand. Once dry, you can perform scratch and tape tests to ensure good adhesion.

Detail Paint

Now for the fun part, the details. Do not add any black weathering until the last step, but you can add other colors and white weathering at this stage. Tape off areas for color and use cheap matte acrylic craft paints as much as possible. If you have a compressor, you can use a small paint sprayer to apply it. Otherwise, use a very dry brush along tape edges so it does not bleed under the tape or use a matte clear paint to seal the edges first. Once these colors are dry, you can use folded 220 grit sandpaper on the edge to add scratches. Some of the more distinct scratches can be added with paint and a fine brush. Then sand with the flat surface of your sandpaper to make thin spots in the paint. The colors should be a little lighter and more vibrant than your references because, when you weather with black after clear coating, these colors will darken. Someone posted the 3D models, which make for excellent references.

Enamel and Final Weathering

Before final weathering with matte black acrylic, seal your work with a solid coat of satin enamel finish. I use Rustoleum satin clear enamel. Wait overnight after applying the sealer to all surfaces, then mix matte black acrylic with a little water, apply in grooves, and wipe away quickly with a small damp rag. Spread it over open areas and remove most of it quickly. If you get too much black, you can wet the rag and wipe away. If it does not wipe off enough, 70% isopropyl alcohol should remove it. You can use a fine brush to add watery black to grooves you would like to better define. After the black weathering dries, I recommend using some folded sandpaper to add scratches with the edge, which makes for some brighter white scratches in the weathering.

Now you are ready for strap assembly.