Do panel lines like a pro!

That's cool Pete.

I used Rapidograph pens when I worked as an Illustrator.
As long as you keep shaking the nibs to keep them clear, they work fine.
They do wear out, and begin to scratch when they do.
Also, avoid dismantling them as the fine wire centre needle often buckles when refitting.

...otherwise a very good tool.

The idea is great, but I think in some car it make looks like a cartoonish car.