Summarize this article:

This pipe is considered "pure" because all you need to make it is an apple and stick-like device, such as a pen, with a tip sharp enough to poke a hole in the apple.  Make sure the apple you use is fresh. A soft apple could collapse while you're trying to bore the holes. It's ideal to use the type of ball-point pen with a tip you can unscrew so you can take out the ink well. Otherwise, you may spill ink all over the apple. Once you take out the ink well, screw the tip back on. Don't use a pencil. It's likely to break inside the apple while you're trying to make a hole with it.
Get an apple and a pen.