Use rubber bands to attach this to your wrist like an assassin from assassins creed! It's also fun to fake stab your friends with the retractable version in school because it goes back in and doesn't hurt, just don't get in trouble! (This can also be done with different pen models with similar components)
Step 1: Reusable Version
1.Take out ink
2.thread ink through cap so that the tip is on the inside of the cap
3.put cap back on
4. Reverse the process to use pen
Step 2: Retractable Version
Get A Cheap Pen With A Cap-It has to have a cap and this thing- the little thing at the end that will be removed to gain access into the pen
Step 3: Remove the Ink
Use pliers or carefully use your teeth to get it out (not recommended)
Step 4: Get a Pencil Sharpener With a Big Opening
Sharpen the end part until the little black thing comes out, you should have a hollow tube like this (mine has tape on it because I couldn't find a sharpener like the one i used to have so I used pliers to crack the pen and take the piece out, also it marks the back)
Step 5: Assembly
Ink goes in backwards, then endcap, then cap
Step 6: Ta Dah!
Flick to extend and press down to put back, have fun and be smart, remember there are other pens you could use for this, so don't be afraid to make some things up!