Tolerance Stack-Up Analyzer (2D)

Every manufactured assembly is a chain of parts, and every part carries its own manufacturing tolerance — the design question is how those individual tolerances combine into the total error of the finished assembly. This simulator draws a 2D stack of N parts, each with a per-part tolerance, and compares the two classic predictions engineers use — worst-case summation and RSS (root-sum-square) statistical tolerancing — against a live Monte Carlo production run that samples each part's real length from a normal distribution and checks the resulting stack against a spec window. Watch the stack's end cap flip red the instant a randomly realized assembly falls outside spec, and see the running histogram converge toward the RSS-predicted normal curve as more simulated parts roll off the line.