In order to function, any design must be constructed of specific materials with available techniques of manufacture and workmanship. While closely related to functional issues, quality of materials and constructional techniques can be evaluated separately from functional performance.
The choice of materials and workmanship greatly influences an objects durability andits initial and lifetime costs, values separate from function. A chair can be comfortable and serviceable (that is, serve its primary function) at least for a time even if poorly made of inappropriate materials.
An objects materials and constructional techniques must be appropriate to its intended use. The longest-lasting and. most expensive of materials do not best serve every situation. A temporary exhibit will be built very differently from a monumental space expected to endure for generations. A paper clip and a cup of solid gold can be equally well designed, as long as each suits an intended use and is well made.
In an interior, wood plank floors, plastered walls, and simple wood furniture may be appropriate to one set of requirements while marble, granite, leather, and stainless steel may suit another situation. In each case, excellence requires logical choices and quality workmanship suited to the materials selected.