Another factor, of course, is the material selection. Thermoplastics can vary considerably in price from around £1 per kg for basic polyolefins up to £30 per kg and more for specialised polymers. Even within the more general ranges of commodity and engineering polymers, there is wide variation in price. The density of different polymers also varies leading to potentially heavier parts and higher cost.
This is an area where expert advice, such as that provided by Rutland Plastics, can be of benefit. Although it may be possible to design a part to use a cheaper material, e.g. polypropylene, by use of ribs and thicker sections, it may actually work out cheaper to use a stronger but more expensive material, such as nylon or ABS. Fewer ribs may then be required and the part could have thinner sections.
Material data sheets can only be of limited use here with strength and stiffness key properties as outlined in previous articles. It is far better to be guided by expert advice from a moulder or material supplier with experience of a range of applications for different polymers.