Instructables is a very good reference of projects in the do-it-yourself area and the source from where we can get inspired to cut the costs of our projects. The user Appleman assembles this incredible cheap robotic gripper able to grasp an object when it is touched.
In the step-by-step tutorial, we can find how to build the 3D printed robot gripper acted by a servo motor and engineered to close or open the fingers when the object pressed the switch.
The project is not perfect, and there is place for improvements. However, any hobbyist or hacker can build this simple gripper with a 3D printer, an Arduino microcontroller, few wires, and a USB A to B cable.
For full documentation and complete instructions visit the tutorial Single Servo Robotic Gripper.