The sky's the limit pretty much. I've used the Krylon and the Rustoleum on plastic mags. TDB is right.......I'm still a rookie. The Tapco mags are cheap enough to mess with several times. Being creative is fun, and you get more ideas as you go. I've used some oddball items for paint jobs such as wadded up plastic grocery bags,and frayed ends of nylon rope for certain effects. My techniques could be looked at as not well refined or abstract compared to others. While unique and rare, none of mine have fetched over a thousand dollars in the marketplace, but you know they're not forgeries.....and I'll never be famous (for painting mags).
Last month I started painting metal magazines and I'm going to be a bit more diligent with those. The South Korean 7.62 mags seem to be good candidates due to their low price and zero collector value. I have some well worn Polish and Romanian 5.45 steel mags but I'm not going to ruin their value by painting them. If I had a couple of dozen..........................that might be a different story. Y'all know I'm good at writing stories

Plenty of pics on the forum(s) and some you've already seen via the link and in this thread. My first two metal mags here......'mud puddle' and 'cedar'. The cedar mag came out too light for my liking so it's going in for rehab. Base color is foliage green then a cedar sprig was laid over while the FDE was sprayed. Obviously the green could have been darker and the FDE over-spray caused the cedar sprig to be less well defined. They're all basically a work in progress for me until I'm satisfied with the end result. Either way.....if you're just going with a color scheme or trying to match your rifle or pistol and your set up........it's just plain fun to do and experiment with.
It could also take you places that you've never been......such as the ladies cosmetics section looking for cotton balls and sea sponges (yes I have)