A method of manufacturing spectacle arms includes grooving an inner face of a first cover plate to form grooves and providing a gauge with longilineal inserts. Front and rear bridges join front and rear ends of the longilineal inserts and provide front and rear indexing. The gauge is set on the inner face of the first cover plate such that the longilineal inserts are disposed in the grooves and a second cover plate is pressed and bonded on the inner face of the first plate such that the longilineal inserts are inserted between the first and second cover plates. The plates are cut around the longilineal inserts with a cutting tool after the cutting tool is positioned and held in place using corresponding front and rear tool indexing.