Credits

2Papi2Chulo for letting me use their helicopter blades as a base and teaching me how to make them fold

Beetlejuice156 since I used their MH-60R to show the folding rotor blades

Folding blades in action

Helicopter blades folded

Blades installed on Beetlejuices156's MH-60R

Controls

Throttle: fires up the blades
Ag.3: Opens/Closes the blades
VTOL: Controls lift

Instructions

Grab the blades by the joint rotatior located at the base and save it on your subassemblies. You'll also need the VTOL engine and magnet. Connect the blades to your helicopter by the bottom of the rotatior.

Place the magnet close to the stub at the bottom of the build
Now place the VTOL engine anywhere on your build. The blades will not spin without the VTOL engine

Important!

Make sure the stub faces twords the back of the helicopter when you install the blades or else they won't close right!