Had another problem on the same mold.  I'm having difficulties flagging this piece.  I know it looks simple but I'm still new.  I've tried to cut strips of cardboard for a flange and hot glue it around the edges but with all the curves it wasn't working very well.  Then I tried laying it flat on cardboard and building all sides with clay, but that wasn't working either.  It was using excessive amounts of clay.  especially the side on the pic.  Any other suggestions would be great.

Fair point but unless you intend making multiple items, making a mould is a lot of work and money. For some people who just want the carbon look then wrapping is easier and cheaper.