As technology advances, so do the methods and approaches we use in various industries. A prime example is the field of plastic product design. For decades, we have relied on traditional manufacturing methods, but now we're experiencing a major shift with the rise of additive manufacturing.

Additive manufacturing, more commonly known as 3D printing, is revolutionizing plastic product design. It allows for the creation of complex, custom designs with an impressive speed and flexibility not seen in traditional methods. This transformation is 'breaking the mold' of what we thought was possible in plastic product design.

Traditional plastic product design requires making a mold, a process that can be costly and time-consuming. Moreover, once a mold is made, altering it for design changes can be difficult and expensive. With additive manufacturing, there's no need for a mold. Designers can create intricate shapes, even ones that were previously thought impossible, without the constraints and costs of mold-making.

Additive manufacturing also excels in customization. Unlike traditional methods that focus on producing identical items, 3D printing makes it possible to create custom plastic products. This gives designers unprecedented flexibility to tweak and refine designs on-the-go, taking innovation in plastic product design to new heights.

Another significant advantage of additive manufacturing is how it accelerates the transition from design to production. Whereas traditional methods may require weeks or even months for mold changes and adjustments, additive manufacturing allows for rapid prototyping. Businesses can test designs quicker, iterate faster, and ultimately bring products to market in a shorter time.

Lastly, additive manufacturing is making strides in sustainability, a critical aspect in today's environmentally-conscious world. 3D printing produces less material waste than traditional methods, contributing to reduced environmental impact. This shift towards more sustainable practices is yet another way additive manufacturing is 'breaking the mold' in plastic product design.

In conclusion, additive manufacturing is more than just an alternative to traditional manufacturing methods. It's a transformative approach that's changing the face of plastic product design, offering a quicker, more flexible, and sustainable production method. As we continue to embrace and optimize this technology, the possibilities for future design innovation are limitless.