MAXJEEP

whe about the 55 gallon drum as a side draft or hood and 2 sections of 8 inch double wall insulated flue for the chimney? either that or I think I will use large 10-12 B vent with flashing and a cap 

I live in ohio east of Cincinnati . What would you use for a cap and flashing on spiral duct?  

How about using b vent pipe flashing and a cap. I have a steel roof and b vent comes in 12 inch diameter it is relitively inexpensive and somewhat insulated due to the air gap. Then inside I could attach it to a good or side draft box. 

I am new to all this but have a young son who loves it.  I built a 10x10 lean to with a steal roof and a crushed limestone floor.  A neighbor gave me 8 inch double wall wood stove flue pipe, cap, flashing, and celing support.  My first question...do I cut a hole in the steal and screw  the flashing to the inside and caulk the heck out of it?  My roof is the standard pole barn steel...not flat.  It has a 3- 12 pitch.   My second question.. Do I build a side draft or a hood.  The building is not air tight.  The walls are dog ear fence and I lined the inside with left over roof steal around the forge while leaving 25-30 inches from the fire pot to the walls.  I thought of using a cut 55 gallon drumb for a hood or a 25-30 gallon drumb for a side draft stack and attaching the double wall pipe to the top,of it. Just looking for advise.  Will any of these ideas work?