I plan on doing that too, but haven't started experimenting. I am going to try rubberbands or small springs, magnets & a trigger latch that holds the blades closed under tension. I have a hollow grapple rocket, so that will make it easier.
Is there anyway way to get it apart and see how the wings are made internally. If they could be modified, I would think that the easiest way to actuate them would be to attach a solenoid. The solenoid could be triggered by a concealed switch or button.