Hi Paul, I think you can get polyimide thicker than 175 microns. It may not go as Kapton, but maybe as Cirlex or Torlon or something else. I think goodfellow.com carries these in millimeter thick sheets and rods, and that they're still radiation and heat resistant. Goodfellow tends to be pricey, but has excellent information on thermal and mechanical properties. Using MgO, sapphire, or even diamond might be reasonable too. --Matt PS: I have a working build of PGPLOT with all of Aquaterm, X11, Postscript, and Png devices on Mac OS X. I'm still tweaking the makefile so that it links directly to the png objects to avoid possible conflicts with dynamic png and zlib libraries, but I should have a working ifeffit binary using this in a matter of days, and then be ready to tweak horae's Makefile.PL so that horae_update works.