Where are you located? In the US, you can get “LA’s totally awesome” at the dollar store, that stuff is magic and gets paint off without attacking the plastic/resin. (as others said, metal is very forgiving, just throw it into pure acetone for a couple of seconds and you’re good). Whenever I am there, a bottle or two make it back to Germany.
For the stripping itself I use an ultrasonic cleaner, like it is also used to clean jewellery and stuff like that. You can get one for around 30 bucks on Amazon. Also great for cleaning resin minis before glueing/priming.