A Dremel is a marvelous, multi-use tool available in most home improvement stores. It’s a small rotational motor. Dremels are designed to be used with numerous bits serving different purposes. It can act as a drill, a sander, a grinder, a small saw, a polisher, etc. It’s great for eating through areas of unwanted plastic, or cutting though medium-sized chunks. A basic set can start around $75, and is probably the best investment a customizer can make as far as tools are concerned. Easily found at most home improvement stores.
If you can , get the cordless variety. Much less fuss!