Ben Slayton has come up with an excellent way to improve safety for his 2- and 3-year-old children around his home in Nashville, Tennessee --and he has shared the device design on Thingiverse. It's a 3D printed Ninja Lock--Indoor Child Door Lock. It's a simple device that fits over the door at the top and is able to keep the door in place at a width where children can not fit through. Even better, he's figured out how to also avoid that looming childhood scourge: slammed fingers. Now this is a functional design with an excellent mission of keeping children safe from going into rooms or outdoors unsupervised! Check it out at 3DPrint.com: http://3dprint.com/98401/3d-printed-ninja-door-lock/