A forming tool for a cotter pin is provided that includes a frame configured to mount to an electric tool, a pneumatic cylinder disposed on the frame, and a manipulator coupled to the pneumatic cylinder and configured to separate legs of the cotter pin. A system for forming a cotter pin is also provided that includes an electric tool having a rotatable head and a switch, and a forming tool coupled to the rotatable head that is configured to form legs of the cotter pin, and wherein the switch is configured to initiate an automatic forming sequence to form the legs. A method for forming a cotter pin is also provided that includes positioning a forming tool over a screw shaft through which a cotter pin is disposed, aligning the forming tool with legs of the cotter pin, and initiating an automatic forming sequence.