this model takes acrylic board to make it first.then add four battens on its bottom to strenghthen it, then add a big piece of fiberglass on its body,and the sides of the bathtub will add a piece of fiberglass once time.then in order to steday the bathtub,we add four iron hob on its rims. as a manufacturer,we can produce the special products you want,we also can put the material as your request.