If you want to play with the design, make it out of Styrofoam. There are places online and some craft stores than offer hotwire sculpting/modeling tools to use when shaping the foam.

 

Once you have a designed modeled, take it to a foundry and have then cast it in aluminum. It’s not that expensive and you can make your mistakes in relatively cheap material. Use 3m 78 spray adhesive to join foam pieces together. Use only Styrofoam.

 

T Mann