On Oct 21, 8:41 pm, "BETA-32" wrote:
I need to cut 2 rectangular openings in an existing HVAC supply and return
ducts.

How can I do this?

I've tried using a power jigsaw with a metal cutting blade -- big mess.

I see things like power shears when I do Google searches, but that seems
like a whole lot of money to spend to just cut the 2 openings.

Are there any hand tools or cutting chisels that will work for this?

Any other suggestions?

Here's a DIY video on how it's done. Although this is for a circular
collar, its similiar for a rectangle.
http://www.youtube.com/watch?v=gSN6L2KgDNA