Need to make a sheet metal fitting

[Kungur]

As a woodworker I am a bit stumped and hope you guys can help me out.
I am doing some work at home and have a 2 1/4" x 10" duct that wil come out under a cabinet. Problem is I need to center it on the cabinet and I need an offset. I think I can cut the right "curves" but how do I attach the sides,2 1/4" , to the top and bottom, the 10"? I asked a few sheetmatal shops and they have a 4-5 week wait. So...
Thanks in advance

[BILLG]

As a woodworker I am a bit stumped and hope you guys can help me out.
I am doing some work at home and have a 2 1/4" x 10" duct that wil come out under a cabinet. Problem is I need to center it on the cabinet and I need an offset. I think I can cut the right "curves" but how do I attach the sides,2 1/4" , to the top and bottom, the 10"? I asked a few sheetmatal shops and they have a 4-5 week wait. So...
Thanks in advance


first make the top and bottom piece, then when you make the sides make them 3 1/4" and bend a 1/2" lip on top and bottom of piece, then rivet lips to top and bottom 10" pieces.

http://www.ridgidforum.com/photoplog/images/238/medium/1_DSC00387.JPG