[kach22i]

I need to cut four 6" or 7" holes for installing round metal ductwork.

What is the best way to do this?

I'll be cutting through thin fiberglass, ABS plastic and five inches of rigid foam (hovercraft).

I was not sure until just now if the openings were going to be square, round or odd shaped so I picked up a 7 amp reciprocating saw from Harbor Freight ($5 off coupon plus last day of sale = $32).

I'm going to make a cardboard template using drafting tools, and mark the cut holes with a magic marker. If there is a better way to cut holes, I'd like to know. Some of the working areas may be tight and I might end up on my back.