I started by fencing off sections on both sides and forcing clay soaked straw in. This was very time consuming and also did not provide the best grip for the subsequent plaster layer.
I later switched to fence boxing the sections and force filling them with treated wattle branches. This is then bound together with a cob straw bind which is forced into the fencing and binds to the sticks in the wall. This works a treat.
Note the mixing tool.. best tool ever for mixing cob and clay! And cement.
I just welded a galvanized pipe over the biggest drill bit I had and the welded 2 mixing bars on it.