A method of constructing curvilinear structures utilizes an armature mast, an armature boom having a vertically and horizontally pivotable arm terminating in a reinforcing rod (rebar) tying guide, and associated hardware. The tying guide is aligned with a piece of vertical rebar, and a separate piece...http://www.google.es/patents/US5305576?utm_source=gb-gplus-sharePatente US5305576 - Method of constructing curvilinear structures
