Here are some of my cool as branch pens!
Making them is very simple: all you need to do is cut off a small branch about 1/3 inch diameter and well as long as you like really but i would recommend you stick to the regular size of the average pen. Once you have done this whittle one end, not quite to a point, and then carefully drill a hole, down the center of the branch, about 5 centimeters long. Now you can pull apart a normal pen, chop the ink cartridge to size and squeeze it up the hole you just drilled. By the way the fit must be very tight and stable otherwise it will either always fall out or wobble when you try to write.
Hope you liked this and simply tell me if you want steps for this as i am more than willing to if you want!!!