I love covering pens and these were not only fun to clay with but feel really good when they are put together and have a nice weight to them. The first set below I used the same "seamless" method I use to make my textured tube beads and my fan/light pulls. I discovered it works great for covering pens as well! I'm writing a tutorial for this and should be published in a few weeks.
There has been a lot of talk on the net lately about covering pens. Surfingcat did some experiments with different pens that are good and not so good with claying and melt when heated. Then Angela from Crafty Goat created an interesting blog post on the top four pens she discovered are oven safe. I really like the Bic retractable one and think I might try some of those next for a more affordable and practical type pen to sell to replace the typical stick ones.