Quote Originally Posted by chris-uk View Post
Not sure that I'd have to throw away a box because one of the holes cracked. It's not like the plastic doesn't hold together perfectly fine. If you're using more brittle plastic it may be different.
The plastic doesn't hold together perfectly fine anymore. Sometimes the crack extends from one hole to another, or up to the edge of the box and you do lose structural integrity. Then, with a little warping from a load or heat, and an exceptionally tenacious little snake, you may well end up with one escaping or getting itself killed. And sometimes a piece of plastic goes flying and that 2 mm hole you were drilling suddenly becomes a 2 cm hole.