I would like to start a thread on wacky and complex homemade nerf gun designs. I have some that may work or would just be pointless, but here are mine anyway.
1. Fully Auto LOUD Pulse jet nerf blaster
this one is a bit ridiculous, where you build a valveless pulse jet and stick the feeder onto the exhaust, and some insulation to prevent your skin to be burned, but imagine having a fully auto nerf gun that uses only some fuel and physics (with extremley loud noises)
2. Fully auto brushless motor nerf blaster
now, nerf has made guns like this, but semi auto. I was thinking getting two brushless motors (outrunners for less noise and higher rpms, inrunners for more torque), attach some flywheels, and a spring loaded dart feeder. This will be noisy (not as noisy as the pulse jet idea) but expensive and might not perform well, but will definitely be fun.
3. musket style nerf gun (using some alternative to gunpowder)
this will be dangerous, potentially slightly illegal if using gunpowder, slow reload times, pointless, fun, and a slight chance of malfunction resulting in an explosion blowing off big chunks of your skin. This thing is simple. Single shot. This thing is practically a musket, except built out of PVC and fires foam darts.
Post your inventive, pointless, dangerous, illegal, expensive, crazy, explosive, and complex designs here. Lets see if anyone can get a design to actually work!