The horns have a lightweight material as a base form to help lighten the over wearing weight, but yes, it's all a mixture of epoxy putties and clay except for the silver details, those are enameled metal stampings that have been cut and reshaped to fit the design. The green 'stones' are acrylic with a protective coat of clear enamel to protect them from getting scuffed or damaged.
Awesome, it looks great!