I've used the RIT dye process on AR and AK magazines. It works great. Magpul has mags that are plain white, ready to be dyed. Sig also has (or had) frame that you could color using the same method. The color choices of fabic dye are more or less limitless. So if a fuchsia frame is your thing... go Sig.
I painted a 7.62 suppressor with the Brownell product. FDE. It came out OK. It was durable but over time it discolored a little from heat. Cans can get very (red) hot so I wasn't terribly surprised. Later, that suppressor suffered a baffle strike that ended its life.