I work in the automotive finish industry. 3M makes all kinds of protective films you can cut to custom sizes. they are mainly intended for protecting the paint and headlight lense but would actually make good electronics protection.
but you can get the purposly made material from them also http://solutions.3m.com/wps/portal/...E3E02LECIE20GER4_nid=845TL8QBJBbeWZX7L0FD3Fgl