plastic and rubber 3 d shape

I am looking to get a series of climbing holds made for me. They are for childern and need to be able to support 15 stone per hold. They need to be very cheap ideally made of a strong plastic with a rubber skin that does not move. I have 5 shapes in total. rock climbing holds are very expensive. I am looking to make some low level kid traversing ones. So i need some one to help design and price a cheap strong safe alternative.