Hey guys, I know it's been a while, and I'm new to these.
Anyway, at about 7PM, I was bored as hell, and wanted to do something. I saw a pen, tape, and some cans and thought to myself, IMA GO MAKE SOMETHING! So, I did, lol. Anyway, this is a fairly easy thing to do, and only takes about 10 minutes to make. This is designed for connector pen lids, but I guess you could put something between the rubber bands to make it fire anything. Anyway, enjoy!

Step 1: Parts

This is all you will need. Easy!

Step 2: First Things

Okay, what you will need to do is pull apart the pen, and attach the elastic to the ring pulls.

Step 3: Now Here Comes the Tape...

Yep, you heard me.

Step 4: Moar Tape

Tape, once again...

Step 5: Firing

There was already a demo of this is the vid, but whatev. Anyway, get a connector pen lid, place the rubber bands in the connecting part, pull back, and let go. And there you have it!