Originally Posted by Sully1742
Did you try scoring the plastic? Take a metal straightedge and a utility knife. Score the line with the knife a few times, then give it a firm and quick snap with your hand.
This was the method I found worked the best for me. It is neater and has sharper, crisper lines. I did use the dremel some, though the plastic does get very hot and will burn you if it hits you while you cut it.
If you do go with the dremel tool do as a reply said and use the sanding disc, cuts much better and is faster than drilling.