Electronic – How to open a rectangular hole on a metal case

casesphysical-design

I'm working on a case design. There is rectangular switch. I am trying to open a rectangular hole on the metallic case to fix it in there. I'm not doing a good job, if it goes on like this it looks like I'm going to ruin the case at all.

How do I open this hole?

Switch and the imperfect hole #1
Picture #1

Switch and the imperfect hole #2
Picture #2

Dimensions of the rectangle is 20.0mm x 25.4mm.

Best Answer

There is the tool exactly for this, named nibbler. They sell it for $10 in Radioshack.

enter image description here

enter image description here

Specialized hole punch for specific shapes:

enter image description here

For most advanced holes there is a special drill even For most advanced holes there is a enter image description here