Mock-ups have an intrinsic value, but they come with a cost. What do projects gain from including mock-ups? What do projects give up without mock-ups? What are different kinds of mock-ups, and how are they best applied? When can in-place mock-ups substitute for dedicated mock-ups? What parts of projects benefit most from mock-ups? When and how can mock-ups be misleading? This session will share and analyze laboratory module mock-ups from several completed projects. Drawings and specifications for mock-ups will be shown and compared to completed mock-up photos, illustrating challenges of defining mock-up scope. Photos of dedicated mock-ups from specific projects will be compared to similar in-place mock-ups from other projects. Specific advantages and disadvantages of each technique will be discussed. Final installation examples will be compared to their mock-ups, highlighting challenges and opportunities of mock-up reviews.