Here is a custom dart blaster that is still a work in progress, dubbed the Arbalest.
The version you see here is the first prototype, made almost entirely of cardboard. There is some EVA foam acting as traction for two zip tie mounts for each motor, and some structure/functionality is provided by craft/popsicle sticks. Some structural integrity for mounts is also provided by cut up loyalty/gift cards, to ensure the cardboard isn’t shredded by torque.
Yes I said 120 rounds per second, I meant minute. I have not done any range tests of yet, as I am waiting until I can ensure better balance between the flywheels, which were hand made and exhibit some resonance issues that cause the blaster to vibrate and be quite loud at higher RPM operation.
The name “Arbalest” comes from a type of crossbow used in 12th century Europe, and was quite powerful and accurate. ( http://en.m.wikipedia.org/wiki/Arbalest)