Background: The aim was to investigate the utilization of CAD/ 3D printers for designing and manufacturing custom trays, which is one of the steps in the fabrication of complete dentures. Materials and methods: The samples included 36 trays on maxillary casts of edentulous mannequins that were divided into 6 groups (n=6) as the following: Group 1: the trays with selective pressure produced using CAD/3D printer, Group 2: the trays with selective pressure fabricated using cold-cured acrylic resin, Group 3: the trays with selective pressure fabricated using light-cured resin, Group 4: the trays with space using CAD / 3D printer, Group 5: the trays with space fabricated using cold-cured resin, and Group 6: the trays with space fabricated using light-cured resin. The distance between the tissue surfaces of the trays was calculated using MATLAB software. One-way ANOVA test was used for statistical analysis, and P<0.05 was considered as significant. Results: There is a significant difference between groups 1, 2 and 3 (P=0.001). Pairwise comparisons with post hoc Tukey tests showed that the mean distance in group 2 was significantly higher than those in groups 1 and 3 (P=0.001); however, the mean distances between groups 1 and 3 were not significant. There were no significant differences between groups 4, 5 and 6 (p = 0.53). However, the mean distance in the trays fabricated by the 3D printer was lower than that in the trays fabricated using cold-cured and light-cured acrylic resins. Conclusion: Adaptation and space distribution in the trays fabricated by the 3D printer was more suitable than the conventional trays.