The process of design is strictly regulated and has to be completed step by step, according to the established phases. The major objective of the design process is to complete the design tasks specified by the client. As designers have to deliver design projects of different nature, they need to follow a specific model of professional behavior in order to present a successful project.
Typically, engineer designs projects through following the following scheme of actions: communication with the client regarding clarification of project details; establishment of objectives and constraints for the object; identification of functions intended for the designed object; clarification of requirements of the client; generating alternative ideas for the designed project; project analysis; testing and evaluation of suggested design; optimization of design; and, communication of the documented design project to the client. These steps are completed regardless of the design process model engineer takes: prescriptive or descriptive.

During the process of design it is essential to clarify with the client as much information as possible, especially on the intended goals and objectives for the designed project, and the ways it could be restrained or limited. It is important to estimate the functions the designed object should have and the requirements it is intended to fulfill, because after receipt of the internal feedback from the client during the design process, engineer will have to proceed with thinking of some alternative solutions for the design project. If the design concept requires changes, alternative ideas should be offered to the client. After the design concept is chosen, it should be tested and evaluated against the restrictions, constraints and limitations specified by the client; the object’s functionality and consistency with objectives and goals should be evaluated. All objects are tested by creating a prototype and putting it into testing environment relevant to the real-life conditions. After evaluation is completed, the design concept needs to be refined and optimized, and after thorough analysis and adding all required changes, the final design project can be documented and communicated to the client for final evaluation and implementation.

The descriptive design model consists of three phases: 1) generation, 2) evaluation, and 3) communication. At the first phase, engineer develops the idea on several design concepts. At the second phase, the chosen design concept is tested for consistency with objectives and against constraints intended for the project; functional load of the object is tested. At the third phase, the optimized design concept with final changes is communicated to the client, producers and manufacturers. In terms of this model the design process undergoes the following evolutionary steps: from specification of the design task by the client to the documentation of the final design with completion of consecutive stages of design formation: conceptual design, preliminary design, detailed design, and final design. According to the descriptive model, the design process can be described as follows: statement of client’s ideas, definition of challenge, conceptual design, preliminary design, detailed design, communication of design, and documentation of final design.

Prescriptive model of design process is based on the steps engineer has to take to complete the design task. Those are the same steps from the abovementioned scheme of actions that each engineer completes, but divided according to the phases identified in the descriptive model: framing (objectives and values; constraints; revision of client’s ideas); conceptual design (functions; requirements; means for implementation of functions; alternative solutions; refinement; choose design concept), preliminary design (analysis and evaluation of chosen design), detailed design (optimization and fixing of chosen design), and communication of design (documentation of final design). After the final design is communicated and implemented, external feedback from the end-users is required.

In conclusion, design process consists of several stages that are required to be completed: identification of the challenge; brainstorming (developing design concepts and alternatives); choosing the best available concept; testing and evaluating it; fixing, refining and optimizing design concept; documentation of final design with justification of all changes and communicating it to the client. After receiving a final external feedback from the end-users, the design project can be referred to either as successful or not, and design could be iterated for future use of the project.