Starting from a quick sketch
For this exercise, let's start with something useful, and somewhat simple. But since we're going to 3D print it, we'll make a fun design.
I started by making a pen and paper sketch of my initial concept—a hook-shaped, low-resolution version of a seahorse. I then scanned the image into a JPEG file and saved it to my computer. As you can see in the following figure, it's not a great drawing, but rather a starting point: