I am trying to use top-down design to develop bent pipe openings.  All parts are made in-context, then saved externally.  I've done alright until now.  I need to put membrane (1/4" thick plate) between various tubes to form a gas tight barrier.  When the membrane is between two adjacent tubes, it was simple enough.  But now I need to put the membrane between non-adjacent tubes as the tube in the middle bends "out of plane" (3D).  How do I use one part to cut out another part in an assembly file?

I need to do this in-context because the customer keeps changing their mind about the size of the opening.

I'm using Solidworks 2010 sp4.

Thanks,

Dave