By the way, this launcher was made from materials from my grandma's 'craft area', so I realize that it could be made stronger.
Step 1: Materials
Two paper towel tubes, one that fits inside the first,
A rubber band,
A paper clip,
A shoe lace,
And, a knife.
Warning - This is dangerous, flammable, toxic, pointy, or all of the above. You may very well kill yourself doing this. I am NOT responsible for you being an idiot.
Step 2: The Chassis
Step 3: The Mechanism
Then, take the styrofoam and cut a piece of it the same size as the towel tube just cut(above).
After that, put rubber band through towel roll piece and insert styrofoam, cut circle same diameter as roll, then put it in and pull rubber band taught.
Step 4: Assembly
Put the shoelace down the end of the paper towel roll 'barrel' without notch.
Step 5: Loading / Firing
Drop taffy down barrel, aim, and FIRE!