Dildo-generator is a "user friendly" (although I struggled to make anything that looked even remotely like somebody would want it inside them) website that allows users to design their own sex toys for 3-D printing. After creating the ideal dimensions for your dildo/buttplug (I suggest something at least a foot and a half tall), you can then have the model 3-D printed in silicon or -- OR -- have a mold printed in plastic instead so you can pour the silicon yourself and set up your own dildo factory in the garage! Oh, honey...don't go out there. I, uh, the lawnmower exploded.
Keep going for a shot of a 3-D printed mold and the resulting silicon dong.
Thanks to lebeeps, who agrees homemade sex toys are often the best sex toys. It's kind of like growing your own fruits and vegetables -- they just taste better.