Using a 3-D pen with a tennis ball used as a form
One of the big disadvantages of a 3-D pen is the lack of precision. Unlike a 3-D printer the 3-D pen relies not on a computer but on how skilled you are with your hands. However you can compensate on some things by using a form rather than just creating freehand. Here I am using a tennis ball as a form to create a Christmas ornament, but realize that any ball that can withstand the heat from the pen can be used. And any size ball can be used to create even more than just ornaments, such as using a basketball to create a lampshade. You may wish to cover your ball with masking tape or some other material so the plastic does not melt into the ball. I'm using the tennis ball basically because that is what I have handy and the plastic adheres enough to the ball to make it easy to control. The disadvantage of using a tennis ball is all the small fibers that the plastic adheres to. This can make removing the finished ornament rather difficult. The trick I use to overcome this is the use of a old painter's palette knife. Using the knife as I work, I periodically carefully lift the plastic off of the tennis ball. A thin blade screwdriver could also be used in the same manner. Just be sure to lift the plastic as you work rather than trying to do it all at once at the end. If you try to wait until the end, it becomes extremely difficult to lift the plastic without breaking it.
Once you have removed your ornament you then can began to remove the fine hairs with a lighter or hot knife. Be sure and move quickly so as not to melt the plastic ornament you're working on. Most of the ornaments that I create are shaped similar to a half finished death Star. If you wish to create a full sphere, you need to create two halves and then weld them together after you have removed them from the tennis ball form. One trick I use is to create the ornament using the lines on the tennis ball, rather than a straight half circle. This also helps hide any seem that is created when I weld the two halves together, as it is not a straight line.
Once you have removed your ornament you then can began to remove the fine hairs with a lighter or hot knife. Be sure and move quickly so as not to melt the plastic ornament you're working on. Most of the ornaments that I create are shaped similar to a half finished death Star. If you wish to create a full sphere, you need to create two halves and then weld them together after you have removed them from the tennis ball form. One trick I use is to create the ornament using the lines on the tennis ball, rather than a straight half circle. This also helps hide any seem that is created when I weld the two halves together, as it is not a straight line.
So here we have our finished ornament and all that is left to do is to add a bit of thread or ribbon to hang it by. We can also add lace, beads, crystals or other decorations to the ornament as well as sand and paint the ornament as needed. The type of artwork you use is up to you and I have personally created ornaments for all the seasons, not just Christmas. So have fun and enjoy creating a little bit of artwork with your 3-D pen.