In non-0G environments, the Fisher Space Pen tends to reduce its potential energy by rolling down even the slightest incline. Its beautiful bullet contours offer no resistance. The 3-D printable Space Pen Loss Inhibitor quickly slides on allowing the pen to stand ready for launch or on its side securely. Rocket fins heighten the space theme. May work on other pens, especially if scaled. Post in the comments if you find other pens that work. Not useful in 0G, though still appropriate.