Best tool for cutting roof vent opening?

[wcurtin1962]

I got both sawzalls and a angle grinder. I'll use the angle grinder because I have a better touch with it.

 

[breeze]

Pay a vendor to do it, and ask them. It takes 500 times of doing anything to be an expert! If you plan it out correctly, that's over 95% of it: knowing what to do. Making a business liable for perfection: priceless.