Rapid prototyping is a revolutionizing technology extensively used in automotive, aerospace, medical, jewelry industries etc. Rapid Prototyping is an additive / subtractive layer manufacturing process, used to quickly fabricate a scale model from CAD data in just a matter of hours. In Automotive trims, rapid prototyping technology is a boon. It is used: -To simulate the "tooled up/production part" in terms of assembly, defined function and fit & finish. -To evaluate & capture early feedback from top management review in term of aesthetic, design, etc. -For early prediction and plan of action towards improvement for craftsmanship. -To reduce design iterations, product lifecycle time and cost. In this paper, we will discuss on technical aspects of how prototype models have been effectively put to use in order to validate Packaging, Assembly & Accessibility, Mechanism, Proof of concept, Functionality and Craftsmanship. In TUV 300 door trim were designed to package one-liter water bottle. A prototype was made based on the CAD data using the RIM process. An issue was observed in proto parts. The one-liter bottle was not staying in its defined position. The design was studied for the concern & modified for serial production tool. Since the concern was identified in the Proto stage itself, this issue was not reiterated in the production tool which lead to saving of Tool modification Cost and Time. TUV 300 spare wheel cover was designed with reference to service tire. A Proto part was made to conduct early check for photometry cone requirement of tail lamp as a homologation requirement, Pokey okay, assembly prove out on vehicle, Theft protection and lock packaging. During proto fitment trial, the spare wheel cover was found to be oversized and odd in side view. The craftsmanship was compromised as the spare wheel cover was opening wider at the periphery and the vinyl wrapping was far from acceptable criteria. Necessary modifications were made in design and the part was re-engineered for desired result with all relevant input. All the above concern resolution not only saved time and production cost, the final result a first time right product with enhanced fit and finish.