Consider a low voltage, lightweight (12 gm) solenoid, like this one: Mini Push-Pull Solenoid - 5V : ID 2776 : $4.95 : Adafruit Industries, Unique & fun DIY electronics and kits
Much smaller ones can be found -- these ones weigh only 1.6 gm
Consider a low voltage, lightweight (12 gm) solenoid, like this one: Mini Push-Pull Solenoid - 5V : ID 2776 : $4.95 : Adafruit Industries, Unique & fun DIY electronics and kits
Much smaller ones can be found -- these ones weigh only 1.6 gm