I mentioned this in passing the previous post on my guide to make your own Dactyl Manuform Keyboard. Spray painting your printed things is as easy as it seems. Three things, filler / primer, color, and clear coat. Sanding in between layers. That's it.
Step 1: Filler / Primer
They're the same thing, you just want the grey stuff. Very easy to sand. I started with 240 grit sand paper for the first 2 layers, and 400 for the third / final layer.
Step 2: Color
I chose copper color paint, 2 layers, sanded with 400 grit then 800. Then another thin layer before clear coat.
Step 3: Clear coat
I picked glossy coat for that metallic look, just a couple of thin layer with minor sanding with 1500 grit just to smooth things out. And we're done.
I personally not a fan of glossy shiny things, so I'm going to weather everything with my dark teak wood stain leftover from my keyboard project. This part is also simple enough, spread everything until it's black, then quickly wipe everything off with dry rag. The remaining stains will give the thing its grungy look. I also added the matte clear coat to make it looks older. The result is pictured on the top of the page.