how to put in clear windows?

I got these rc cars called "race tins" anyways i wanna cut out the windows and put in clear plastic but was wondering what was the best way to do this and using what for the clear plastic? thanx

Use clear styrene for the windows. But its gonna be a pain, since most windows have compound curves.

could u use say a hair dryer or a heat gun on the lowest setting to slowly "mold" the shape?