Something as usual as a hand tool, now it usually has a grip with different plastics with two definite areas or more, each one with a different purpose. This is clearly different from decades ago, creating a more modern look and improved functionality.
Although more than one perhaps might be guessing how these pieces are done, and it's a question with multiple answers due to the existence of numerous techniques.
Even with the risk of leaving some important one in the oblivion, let's mention some of them to give a general view to aid the curiosity. Normally some type of mold is implied and also an injection, so there's time to think about possible ideas.
Some manufacturers are focusing molds with two or more entrances to the injection, others use gas or water with the interest of creating different compartments in the mold and release the injection to specific zones. Another technique is a dynamic mold that changes its structure, exposing a zone to other process. Of course, due to the development of 3D printers, a robotic arm or another kind of numeric control representation adds or builds the plastic with several materials.
This opens a door for using recycled materials, mixing chemically incompatible ones creating sophisticated materials with desired properties instead of using traditional methods to achieve the same effect. Newly, polymers are full of surprises, versatility and efficiency.