In some steps you build the ultimate magnetic stylus.
Thanks to Reika for the inspiration
Step 1: Step One - the Magnet
Step 2: The Pencil and the Magnet
the magnet and a Uniball PowerTank ECO, a commonly used pen in geocaching.
Step 3: Disassembled
Step 4: Where the Magnet Fits
Don't cut too much. :)
correct it with a knife until it fits
Step 5: Assemble & Test
Hint: Do NOT glue the magnet. Probably you need to reverse the polarity