Can someone please tell me the best way to cut a register into a basement supply duct? I would like to cut a louvered 6" x 10" register into the supply duct in my basement to help add a bit of heat to the area. I probably want to trace the outline of the register on the duct and then drill four holes (one at each corner) of the rectangular pattern and then use a sheet metal sheers to cut out the sheet metal. What is the best drill bit for cutting into sheet metal, a step drill bit or a metal hole saw? What tools do I need and what's the best way to do this? Thanks in advance for any help.