3-D printing, rapid prototype or make a 3-D model

I am working on a 3-D design project. It will be an artistic wearable crown design, actual size is roughly 20 inches in circumference and approx. 6 inches in height. The weight of the finished crown will be roughly 2-3 kilograms ( 100 ounces). I am looking for someone who has a large 3-D printing machine would could do rapid-prototype or do a actual 3D model using rasin or someone who could actually do a casting with metal. It will be high definition and high resolution finished work.