Pop-up pen

Hi, this is a small project I made for fun. The idea came while I was playing with a pen and a spring popped out unexpectedly. It made me laugh, so I designed a pop-up pen that uses a spring mechanism. 

You will need a pencil with a spring.

Assembly is relatively simple: insert the spring into the pencil as shown in the picture.

Push the part in and insert the pin, as in the photo, you can help with projectile.

Finally, take the projectile, load it in, and secure it by sliding it to the right.

Find your target and flick your thumb in the direction of the arrow to launch the pen.
It might take a bit of practice at first, but you’ll get the hang of it quickly.

The pencil's side is threaded—just like a real pencil—so the parts screw together. But you’ll probably need to shorten the pen refill.
I made a small tool for that, just place it against the refill as shown in the photo, and trim it at the marked point.

If you have any ideas for improvement, I’d be happy to hear them!

Have fun!