Secret Marker
This is a great place to hide small jewelry, small messages, and money/checks. It writes like a normal marker so if someone uses it, they will have no idea that you are hiding things in the cartridge tube. You pull off the top cap of the marker and voila! You can put anything you want in there and no one could predict that is your secret hiding spot. Also, since the ink tip is in the marker, I didn't want thee valuables to become covered in ink. So to prevent the ink touching your valuables, there is a small foam circle right about the ink tip to prevent the ink from getting on your prized possessions. It is easy and cheap to make and takes no time.