Hello.  At my work, we do alot of pipe intersects for sign structures and the shop usually needs a cutout template to lay on their pipes in order to handburn the cutout to accept the intersecting pipe (sometimes that need instead of the cutout template itself, they prefer to wrap a full template around the whole pipe if small enough and just trace the inside cutout from paper template).  Today, they requested one of these and instead of usually developing in our old DOS based 20 year old transpack software, I thought I would try it in SW.  Basically, an 18" pipe into a 24" pipe intersecting at 90 degrees, couldn't get any simpler.  They need the elliptical cutout profile that is shown on the 24" pipe printed on some manila paper to lay on pipe.  I've modeled the two pipes and thought using intersection curve would work but when I try to then use extruded cut at the intersection profile, I get an error.  I made the main pipe into a sheet metal part so I can flatten in.  Any ideas on what I'm doing wrong would be great.  I arbitrarily made both pipes with a 1/2" thin extrude.  Thanks.