These pen come with 3 refills and holds any two of the three. Two refills are ink refills - one black and one red. The third refill though is a PDA STYLUS!!! So first you make the pen by covering the brass tubes with clay. Then assemble the pen and pick any 2 refills, insert them into the mechanism and voila! Done.

Here's a Beautiful 2-Way pen made by Melody Steeples (click for a larger picture).