Since there were now eight rubber band motors, a mechanism was created to release the propellers in sync, but this was problematic. Eventually a slightly heavy but solid solution was found.

Students stretch pre-cut rubber bands to their lips, stretch the rubber bands, and then allow them to contract. The rubber bands grow warmer as they expand and cool as they contract. To Conduct ...

In fact, the force needed to trip the release is so low that [KI4MCW] added a short rubber band to provide some ... prototype looks promising. Maybe a mechanism like this would be appropriate ...