There is a site that gives free instructions on making a cornice board with eith buckram or foam board.
http://www.ClassyWindowTreatments.com
Canadian House and Home also has fabulous ideas and I believe the cornice board is one of theirs too!
There are at least 3 websites that should have the info on making cornice boards from foam boards:
HGTV
BHG
Waverly Fabrics
Hope this helps you and good luck!
HGTV has this one: http://www.hgtv.com/hgtv/dc_windows ... article/0,,HGTV_3542_1372834,00.html
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