Amusingly, I tried. Your job is safe. ;-) I'm a scientist. I tried using a couple of free 3d modeling tools that are programmable in Python, using Claude within VS Code to design a part according to my prompts. It was a simple plate with some holes for electrical connectors, switches, etc. Of course it let me make some noobie design mistakes, such as making the hole exactly the same diameter as the thing that went into it, plus or minus of course. And I would have had to really scrutinize the Python code to notice that I got one of the diameters wrong altogether.

Just judging from this experience, the effort would rise exponentially with the complexity of the part, not to mention assemblies. The designers earn their keep. I get really bad eyestrain with any task that requires staring at the screen while doing fine mouse work, so I just can't use CAD. On the other hand, I can code all day because I'm not closely focused on the screen when I'm typing.