Need to install a stainless steel cooker hood that includes a 'false' stainless steel chimney stack between the hood and the ceiling. Any advice please on how best to cut the stack neatly so that it meets the ceiling exactly, and how to then fit it without damaging the hood, chimney stack or ceiling ? It seems to me that the stack will cover the supporting bolts for the hood, so the hood needs to go up first but then fitting the stack without bending it looks impossible. Or am I missing something - such as instructions 
