Ed,
I'm weighing in, but don't see the need to - most have given good advice. Some trademark owners (that's really what you're dealing with here, not copyright) are highly protective about their marks. They have to be - even a little bit of unauthorized usage can create confusion and dilution, and SIGNIFICANTLY reduce the value of the mark. My firm represents some very large trademark owners, and I can tell you that they regularly enforce against even small guys. Granted, most of the time it is settled amicably when the violator receives a cease and decist letter and complies, but some are obstinate and, at that point, the firm will undertake more drastic measures.
As Alan implied, much of the time, if you pitch the work you're doing appropriately (e.g., VERY limited production, or at the request of an alumni, etc.), the owner of the mark is likely to be flattered and willing to work with you. But, the terms are going to be pretty strict (must be certain colors, must identially match the logo/mark, etc.), even where the cost is minimal. Still, it will be FAR less expensive in the long run to simply ask permission up front. A typical trademark defense (i.e. litigation) can easily reach into the several tens of thousands of dollars, and frequently gets much more expensive. That's not a risk I'm willing to take to sell a $100-$200 pen.
Besides, our pens look too nice to be engraved! How many people do you know who have an engraved MontBlanc, Waterman, or Boone?
As a side note - thanks to everyone for checking in with me periodically! I hope to be able to get back to pen making in the new year!!! Merry Christmas and Happy New Year to everyone!!!!!!