In MacPaint I can paint anything. In your toolbox I can only assemble something with the parts that you give me.
The MacPaint analogy would hold water if you'd let me draw any shape that I want (to be 3d printed), and merely assist by enforcing the basic constraints required for my device to be manufactured and functional (e.g. enough space to put the electronics in, etc.).
In MacPaint I can paint anything. In your toolbox I can only assemble something with the parts that you give me.
The MacPaint analogy would hold water if you'd let me draw any shape that I want (to be 3d printed), and merely assist by enforcing the basic constraints required for my device to be manufactured and functional (e.g. enough space to put the electronics in, etc.).