It's been done before, but here is what I did........
Step 1: Make Your Memory Useful
I found a piece of coral that washed ashore while I was on vacation recently. I don't like things that sit around collecting dust, I wanted to make it a useful memory.
Step 2: Things You Will Need
1. Memory item
2. Magnet from old hard drive or comparable
3. Small steel (preferably flat head) screw
4. Common hand tools
5. Hot glue gun
6. Drill and bit
8. Cold one or two
Step 3: Salvaged From Old Hard Drive
I put the magnet into a vice and bent the metal mounting frame edge to create space between the magnet and mounting frame. The frame is typically non-magnetic metal and the magnet is glued to it. You can stick a small flatblade into the created gap to free the magnet from the frame. The magnet may be too large for just a single pen. I put the magnet between two pliers and snapped it in half. It is very fragile and breaks easily.
Step 4: Hot Glue Magnet to Collectable
Since this is coral, I glued a couple times until I found the perfect location
Step 5: Break Out the Drill
Drill a small hole into the pen cap and insert the screw
Step 6: Sit Back, Crack a Cold One
It's like I never left the beach.