Converting a childs gripper toy into a remote controlled one is not that hard to do. Pick a toy gripper (I show three here). Remove the squeeze handle assembly. This will expose a stiff wire that connects the squeeze handle to the claw. The stiff wire will be used to act as the linkage to the servo arm. Figure out where the servo will mount then fabricate a plate made of thin sheet metal or use plastic cut to size from an old VHS tape box. cut a slot in the arm of the gripper so you can get to the stiff wire (you might have to remove the claw so the stiff wire can be bent)
Step 1: Fabricate Servo Plate
Bend the stiff wire 90 degress upward (or downwards if the servo will go underneath). You might have to remove the gripper temporarily to get the stiff wire bent where you want for the servo linkage.
Use thin sheet metal or plastic from an old VHS case, This will make the servo support holder. Cut the servo support to the size of your servo, cut a slot in the support wide and long enough so the stiff wire can poke through to link up to the servo arm. Screw everything tight.