Most people make them at home, I think? They just get letters/hiragana and cut them out... then decorate with sparklies and neon-colored paper. Some also have foam characters glued onto a black background.
http://ameblo.jp/nyaney/entry-112027...c=thumb_module
http://p.twipple.jp/gbu6w
I think they may use a 'plain' uchiwa as a base for most of them.