-a piece of paper ( I teared it from a notebook )
-a ballpen ( something like the core also works )
Maybe you need something to cut the tape.
Step 1: Split the Paper
Step 2: Disassemble the Ballpen
Step 3: Make the Striker
Glue the tip.
Pull the pen core out.
Step 4: Make the Barrel
Do not roll it too tight.
Glue the tip, too.
Make sure they can slide smoothly.
Step 5: Tape the Rubberband On
Tape another tip of the rubberband on the barrel.
Step 6: Have Fun!
I am going to make a auto refill one
Sorry for my poor English.