Back in college, I started learning how to design industrial products. During my first years as a designer, I created backpacks, sneakers, furniture, and some home appliance projects.
One of the techniques we had to become proficient as industrial design students was 3D CAD (Computer-Aided Design) modeling. One reason is that CAD is the common language among designers, engineers, and manufacturing technicians.
Expressing ideas in a 3D CAD environment helps an industrial designer create more useful prototypes and better handoff design concepts to engineers, allowing than to detect potential issues earlier and build upon the initial models.
When creating CAD models, a designer doesn’t need to achieve a manufacturing-ready result (that’s the engineers’ job) but makes a good enough artifact that allows team members and stakeholders to collaborate and iterate.
So, what's the CAD equivalent for digital product designers? In my perspective, markup and style languages (like HTML and CSS).
Coding interfaces make it easier for designers to create realistic prototypes and test than in the proper environments, like a browser or mobile device. And as happens when using CAD tools, a designer coding an interface doesn’t need to achieve production-ready results, only good enough prototypes.
When I switched from industrial to digital product design, one of the lessons I took was: coding prototypes can be equivalent to creating 3D CAD models. It may take some time to learn and get used to; it is not as natural as sketching with a pencil (or manipulating vectors); it won’t be practical in every situation. But in the end, it will help a lot. It will make some things easier to test and the conversation with engineers/developers much more fluid.