But, I can only be so violent. I want to cut away at the plastic shell, but not possibly damage anything else inside. This calls for paper. If you cut a 2.5 cm circle out of ordinary paper, put that on the business end of a Dremel or similar high-speed rotary tool, then you can use it as a cutting disc for plastic. It goes through thin plastic (soda bottles and the like) as if it wasn't even there. But it won't go through steel or glass, because the paper isn't hard enough.