Not only needle and thread
The specific requirements of the product determine the material of which it is to be manufactured. Protection, insulation, resistance to wear, design, form etc. The function decides the material. In addition, the material which we sew is often supplemented with materials which may give the product special features. Wood, plastic. sheet metal or steel are not uncommon. We buy all the components required for the product we have designed, incorporate these and assemble the product ready for delivery.