3DCS Variation Analyst is a CAD-based software for tolerance and process analysis integrated into platforms like Siemens NX and Dassault Systemes CATIA, providing insight into how part tolerances affect product assembly and fit. It utilizes Monte Carlo simulations and sensitivity analyses to evaluate variation and its impact on manufacturing quality across the product lifecycle. Major companies, including General Motors and Boeing, leverage 3DCS for optimizing designs and improving product quality through detailed dimensional analysis.