While a variety of materials could be used for a given design, there is always a "right" material for each application. Selecting a material is part of good design practice, and it depends of the particular design and chosen fabrication process. Choosing the right material is critical to achieve excellent performance of the product and surely has a significant impact on its cost.
To choose the ideal material, one must identify first the product's design intention and desired specifications.
Next a search for the material characteristics that suits those needs should be conducted until a match is identified. During that process, perhaps, more than one material type is identified, so the selection will continue considering other factors, such as: fabrication processes, enviromental conditions, tactil feel, weight, etc.