physical design - How do I open a rectangular hole on a metal case ...
Jun 22, 2012 ... Clamp your panel upright in a vice, and use a coarse file to square up the hole. ...
Use a dremel with circular cutting disc, then file to shape.
Basic Metalworking - Basic Tools Required for Metalwork
This page was produced after I began looking for general metal-working and ... If
the blade doesn't match up perfectly with the scribed line, the square needs to be
replaced. ..... I prefer to use socket head cap screws for most everything I do.