YouTube is awash in 20-minute videos answering questions we never asked: Can I use tool X to make object Y, I'll cut this thing in half to show you what's inside, what happens if I crush this with a hydraulic press, etc. This is one actually might be of interest to anyone who does ID or makes models.
An anonymous craftsman posted this video of himself creating a car model with a 3D pen. If you have 23 minutes to burn, watch it, otherwise skip it and I'll summarize below.
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So yeah, it's possible, but an incredibly inefficient use of time due to the finishing required.
However, what I did find of potential interest is the technique he used to create the initial wireframe. If you didn't watch the vid, he drew plan and elevation views of the vehicle, covered them with a sheet of acetate, and traced the 2D images to create slices that he then glued into a 3D wireframe.
With certain objects, I could actually see that being a faster or more accurate way to generate a wireframe than the traditional pliers-and-soldering-gun route.