It was suggested to me by a mini sculptor I met that nylon & copper brushes were good for cleaning & polishing without damaging the surfaces of lead & soft-metal pieces. Here in the 'States, I've found a 3 pack of brushes used in the firearms hobby that come with two grades of plastic brush and a soft copper brush - each with a wider head as well as a tiny narrow head that works for fine details. To strip paint, I use an orange cleaner called "LA's Totally Awesome Orange Cleaner", which is similar to Simple Green but available in "$1 & under" stores. Not as powerful as acetone. But it is exceedingly gentle on plastic (I used it on old model kits as well as metal), can be worked with in the kitchen sink (wonderful de-greaser), and you can re-use it a few times for additional stripping duties.