Shock or vibration loads require a product to have a certain level of stiffness. This is related to material use to some extent, but strongly coheres to the overall design. Placing material where needed but also leaving material out where not necessary keeps the overall design as lightweight as possible. Referring specifically to optics, it is important that shock and vibration loads are absorbed; this is often ensured by using a cement/paste. Cracks may occur if 100% of the shock load is transferred to the optics. The cement/paste is used to create a dampened connection between the optics and mechanical interface, thus preventing cracks.
Contamination, rain, salt fog, humidity, immersion, chemicals and, to some extent, dirt and sand help determine material use, surface treatment and paint. For example, parts get anodized to increase the corrosion resistance of aluminum. If required, it is even possible to hard-anodize components exposed to the elements. However, design also plays a role; a product should not contain ‘pockets’ where contaminant build-up can occur.
A large temperature usage range will have the most influence on moving components which are often made of different materials, thus having different linear expansion coefficients. Careful considerations have to be made when designing such parts as there is a possibility for either increased frictional forces or tolerances to go out of scope.