Just an article that popped up as I looked for dye to use on a bit of fabric I’m working with. This will be used in the future, but I have not tried it yet. After reading through the article I advise that you read all the way through to see that it does work.
As always JMHO YMMV 
I’ll have to read through it but that looks pretty cool.
Never thought to try it on plastic but have used the black Rit dye to dye Nylon gears, works very well.
I have used the synthetic version with mixed success for some hard to find pinball parts (my other hobby). I did not try acetone as I did not want to melt the part. The good news is, as he states, when it does work, it goes below the surface, so it’s scratch resistant.
The standard dye is easy to find. Fewer stores sell the synthetic versions.
I get used pots from the local Goodwill to ensure I retain my wife’s goodwill.