Final answer:
Acceptance and sign-off of the conceptual model by the project team indicates consensus on the design, allowing for implementation to proceed. This phase includes building models or prototypes and testing for adherence to criteria, with possible refinement or redesign if necessary.
Step-by-step explanation:
When the conceptual model is accepted and signed off by the project team, this milestone signifies that all stakeholders agree on the design and understand the project plan, which includes the constraints and criteria the model must meet. This buy-in from the team is vital for the project to run smoothly and for subsequent steps in the design process to proceed, which involves implementation. Implementation can involve building a physical or virtual model, creating a prototype, or even beginning the manufacturing of a product. After this phase, the model or design goes through testing and evaluation, where potential weaknesses may be identified and refinements made to better meet the project criteria and constraints. If a design or prototype does not meet the expected criteria, the design team might need to select a different design concept and undergo further development.