This is just an idea for making a really low cost and different style pen holder. What you need is only a water or a pop bottle; cut it to the height you want and make sure keep the bottom. The design is based on the measurement of your bottle, leave 0.5~1mm gap(depending on your printer's error) to insert your bottle in. Then glue it a little bit with super glue on the edge. Then you have it. Very easy to make. you can do the same thing to can bottle or any other containers that you like. Then you will have different shaped and color pen holder.