Purpose: Commercially available stock trays do not usually fit the arch form and are relatively flat in dimensions, leading to a compromised impression and prosthesis. So, the purpose of this study was to categorize resorbed mandibular ridges according to arch width and sulcus depth and formulation of stock tray design conforming to different resorbed ridge forms. Materials and methods: Measurements on master casts of completely edentulous resorbed ridges (n = 280) were done using a digital vernier caliper. Cluster analysis of means of anterior and posterior arch width and posterior alveololingual sulcus (ALS) depth was done to categorize the extremely resorbed residual ridges for the formulation of conforming stock trays. Cluster analysis formulated three categories. Category 1 had a mean anterior arch width of 23 mm, posterior arch width of 50 mm, and posterior ALS depth of 5.5 mm. Respective dimensions in category 2 were 31, 58, and 12 mm, and in category 3 were 27, 55, and 8.7 mm. Means of arch length, ridge width, sulcus depth, and retromolar pad (RMP) angle were used to modify tray flange dimensions. One-way analysis of variance (ANOVA) for K-means and multiple Tukey honestly significant difference (HSD) tests were applied for validation of clusters/categories. Results: Significant p-values in one-way ANOVA for K-means cluster (p < 0.001) and multiple Tukey HSD test (p < 0.001) validated categorization of extremely resorbed mandibular residual ridges in the study. Mean values of other parameters were used to modify the tray flanges. The 135° angle of the RMP with residual resorbed ridge was suggested to be incorporated in trays to accommodate higher angles too. Conclusion: Use of the formulated stock trays, will improve their adaptation to the resorbed mandibular edentulous ridges and hence the primary impression making, which will provide a strong foundation for a successful final complete denture in such patients.