The authors of this study explored (a) body-to-pattern measurement and shape relationships in trouser patterns drafted by two methods; (b) the consistency of these body-to-pattern relationships between methods and between differently shaped bodies within methods; (c) the patternmaking procedures that cause these outcomes; and (d) how these findings impact garment fit, particularly for mass customization. Body-to-pattern measurement and shape relationships were inconsistent between and within methods, making them unsuitable for use in computer-aided custom patternmaking. Most strikingly, pattern crotch shapes were similar within each method, despite the fact that form crotch shapes were different. Patternmaking procedures causing these inconsistencies include (a) use of proportion of noncorresponding body measurements; (b) use of standard, rather than body, measurements; (c) variations in ease as proportions or standard amounts; (d) trueing, blending, and connecting steps; (e) variation between methods of measurements used, in use of proportions or standard measurements, and in steps; and (h) disregard of body shape.