cooker hood ducting?

[S70JPS]

Does anyone know where I can get stainless steel ducting? Square or rectangular section? I need to duct my cooker hood at a right angle to the chimney just over 2M in length. I have looked on the net and only seem to come up with galvanised stuff. Surely my problem is not unique? Any help much appreciated. I have a diagram bit can't seem to get it to paste into the post.

[dingg]

get it made up at one of your local sheet metal works