D-Rex is a battery powered machine gun Nerf compatible.
The bullets are pushed at very very high speed using two DC motors. LEDs make the machine gun very cool. The trigger is connect to a switch that feed the two motors and the LEDs.
All materials is very commun and chepper. Below the list of material.
2x DC motors 8520 (https://it.aliexpress.com/item...)
1x microswitch (https://it.aliexpress.com/item...)
1x 1S lipo battery (https://it.aliexpress.com/whol...)
7x springs (very easy to found into snap pens)
20cm carbon rods 3mm diameter (or other material)