Rubber-Band Bow and Arrow stronger Version, no glue required.
Only for penicls with 8mm diameter.
You can create your own shooting arms! Please upoad your own arms here :)
I have copied some ideas from this (thank you for this awesome thing! But I need a stronger one):
http://www.thingiverse.com/thing:4691
Created with FreeCAD
Printed in ABS, Mendel Prusa i2
Edit (from dryd3418):
You can get the BIG rubber bands at Staples. They Fit perfectly. http://www.staples.com/Staples-Big-Rubber-Bands-24-Pack/product_383318