Take a blank, then form a head on one end, then form the end for the threads.
A second view.
Then shear a hex off of the round head. See the heavy shear marks under the head? These shear marks will be ground off later.
Then roll the threads into the shank.
These are direct tension indicator devices. The first bolt has a direct tension indicating washer. When the bolt is properly pre-tensioned, the raised areas will be forced back down into the washer from which they were deformed. The second and third bolts have break-off tips which are engaged by the impact wrench. When the proper tension is applied by rotating the nut (holding the bolt stationary through the spline on the tip), the tip torques off.
Close up of the tension indicating washer.
Squirters – these squirt out ink when the proper pre-tension is applied to the bolt. The other side of the Squirter looks just like a washer in the photo directly above.
A bolt failed in double shear.