Modlestrip is designed for removing paint without damage to the model. To use 'Modelstrip', you simply plaster your model all over with the paste (few mm thick) in the areas that you wish to remove paint from. You then place the model in an air tight plastic bag and leave it over night.
The following morning, remove from the bag and simply wash the model under the water tap. The paste will wash off and take the paint with it. In my experience of the product, a little light brushing is also required, but it is very successful and it is purposely made for the job: ie is does not attack plastics.
It effectively disolves paint and has no effect on the surface on which the paint has been placed. You can therefore managed to use it successfully to remove paint from metal/brass models as well as plastic surfaces.