It may look just like an ordinary pen but it may just save your life one day. This was something I made in middle school and its been with me since.
Step 1: GET a PEN LIKE THIS
Needs to have two holes to release the guts.
Step 2: EMPTY IT
Take out the guts
Step 3: ADD MORE SPRINGS TO THE TIP
Add one cause if it had three it wouldn't let you use the pen part.
Step 4: PUT IT BACK TOGETHER
Put all the stuff back in the body.
Step 5: FIRE AWAY
Now it's a spring loaded shooter. just push the little trigger on the second hole. Best part is you can still use it as a normal pen.