MakerBot Print is our newest print-prepration software, which supports native CAD files and STL assemblies,
allows you to interact with all your printers via the Cloud, and many other exciting new features.
There are LED calculators for online and offline use, a site that can calculate the values for you is below. If you have access to a smartphone you can also download an LED calculator that makes calculating a current limiting resistor a breeze. Hope this helps out!
I've run a couple of calculations through the site. Connecting them in parallel may work against you, if you can break the LEDs into groups of 2 LEDs you can extend the runtime of your 9v battery by quite a bit. I've included the diagram the site created below, you can visit the site and try other combinations if you wish.