actual delivered food: a prototype is a necessarily inexact and limited approximation of a "real" final product. Further, prototypers make both deliberate and unintended choices and tradeoffs for reasons ranging from cost/time savings to what they consider "important" vs. "trivial" aspects to focus design attention and execution on. Due to differences in materials, processes and design fidelity, it is possible that a prototype may fail to perform acceptably although the production design may have been sound. Conversely, and somewhat counter-intuitively: prototypes may actually perform acceptably but the production design and outcome may prove unsuccessful, as prototyping materials and processes may actually outperform their production counterparts. In general, it can be expected that individual prototype costs will be substantially greater than the final production costs due to inefficiencies in materials and processes. Prototypes are also used to revise the design for the purposes of reducing costs through optimization and refinement. It is possible to use prototype testing to reduce the risk that a design may not perform as intended, however prototypes generally cannot eliminate all risk. There are pragmatic and practical limitations to the ability of a prototype to match the intended final performance of the product and some allowances and engineering judgement are often required before moving forward with a production design. Building the full design is often expensive and can be time-consuming, especially when repeated several times—building the full design, figuring out what the problems are and how to solve them, then building another full design. As an alternative, rapid prototyping or rapid application development techniques are used for the initial prototypes, which implement part, but not all, of the complete design. This allows designers and manufacturers to rapidly and inexpensively test the parts of the design that are most likely to have problems, solve those problems, and then build the full design. This counter-intuitive idea—that the quickest way to build something is, first to build something else—is shared by scaffolding and Thomson's telescope rule. Engineering sciences In technology research, a technology demonstrator is a prototype serving as proof-of-concept and demonstration model for a new technology or future product, proving its viability and illustrating conceivable applications. In large development projects, a testbed is a platform and prototype development environment for rigorous experimentation and testing of new technologies, components, scientific theories and computational tools. With recent advances in computer modeling it is becoming practical to eliminate the creation of a