I added the 3D Printed Nerf Launcher to the Arduino controlled tank. I can control it from my phone via Bluetooth control. I used a standard servo to make the attachment. This gives me up/down capability.
The interface uses 1K ohm resistors to TIP127 transistors to turn the motors on and off. The small servo doing the pushing had its electronics removed and was modified for infinite 360 degree operation.
Here are some pictures of the insides of the tank.
