Once the design and reviews are complete, a prototype build will occur. During the prototype build the individual mechanical assemblies, circuit boards, and other architectural elements are fabricated under the control of the Quest engineering group. These components are assembled and integrated with each other. It is often at this point that the software team actually has their first opportunity to integrate the software with the full system. It is during this phase that the initial assembly process begins to be conceived. This serves as the basis for some of the Design Transfer activities that are yet to come. Quest staff with manufacturing experience review this information and appropriately drive change to ensure a design that can be manufactured.

Once prototype units are built, system debugging occurs to identify any issues with the system. Often there are a number of changes to ensure that the specific requirements and risk mitigations are fulfilled.
Verification of the system requirements is the final step in the process. The protocols created in the design phase are executed and the results documented. The verification protocols also represent the basis for the product testing that will occur during manufacturing.

At the conclusion of the Prototype build the design documentation is updated to reflect any required changes as a result of the prototype build. Depending on the nature of the design, multiple iterations may be built. The intended output is a solid manufacturable design.