clone() {
    const mat = new Materials();
    mat.info = this.info;
    mat.path = this.path;
    mat.apath = this.apath;
    mat.start = this.start;
    mat.end = this.end;
    mat.length = this.length;

    return mat;
  }
Return a cloned Materials object
@return {Materials} A cloned Materials object
@public