I assume this is the Maori symbol or pendant as seen on http://www.lawas.co.nz/LINKS/tikipage.htm  6'-7' seems a little large to hang around your neck!
If you search the Forum you will find several ideas.  One is to use carved polystyrene as the base.  Another is to use a wood armature (skeleton) or one made from proprietory plastic tubing with joints etc.  These would be combined with a general wrap of chicken wire or card or cotton cloth soaked in thin plaster of paris - anything to creat the general structure.
You could then proceed with a papier mache pulp to build up the shape you want.
If it is to go outside, protect it well - again many ideas within the Forum.
David