Turpija, I had a thought.
A long time ago I saw an article on a guy who made what he called a "plasma lathe". He was cutting cylindrical light fixtures with intricate patterns. His software solution was ingenious:
He ran his normal 2D program, which would produce the design as a flat sheet. He connected his Y-axis to rotate the cylinder. With appropriate scaling of steps, or just simply drawing the "flat 2D" to appropriate size, it worked extremely well.
This only helps if drawing on a cylinder, but your pen designs may have cylindrical sections where an intricate vcarve engraving would be nice.