A great Development= Printing with Nylon! Not sure how to source it yet.. and you MUST scrub the fumes... as they are toxic
http://www.3ders.org/articles/20120523-3d-printing-using-nylon-to-make-flexible-parts.html
http://www.3ders.org/articles/20120523-3d-printing-using-nylon-to-make-flexible-parts.html