The Nails of the clamps have been designed to catch an object of small to medium size.
The NAILS when printed will be fixed one to the other. As a measure of printing accuracy: if you can not SNAP and separate the two nails, that means you have printed the Gripper without the required accuracy and the gears will not work as intended. Reduce the layer height and printing speed to increase the printing precision
This is the gripper of the Pybot Robotic Arm: https://www.prusaprinters.org/prints/39958-arduino-robotic-arm-open-source-python-control-app?utm_source=prusaprinters&utm_medium=email&utm_campaign=notif-print-new-rating&utm_content=object
Assembly guide: https://www.jjrobots.com/robotic-arm-gripper-2-degrees-of-freedom/
The author hasn't provided the model origin yet.