ultimate secondary material

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "RIAA/MPAA's Worst Nightmare" <mike.marcum-at-zoomtown-dot-com> 

What's the best material for  TC secondary other than hard vacuum? PE is 
too soft to work with unless it's solid rod (heavy and probably just as 
lossy as pvc overall because of the sheer mass involved). What about UHMW 
PE? Is this stuff hard enough? Acrylic tube comes to mind but don't know if 
that's better RF wise given the same mass.