sir, you have not used the base circle while drawing the involute profile of the gear anywhere. in your design this is not an issue since the base circle is smaller then the dedumdum circle thus the tooth profile ends before the base circle come into play but for gears with smaller modules, like 1.75 or 2.25 etc, the base circle for smaller gears might be bigger then the dedundum circle, thus the part of the dedundum below the base circle needs to be drawn as a straight line pointing towards the center in order to prevent undercutting. please address this issue. Amazing video on showing the construction of the involute profile by the way.