Here is a modular single actuator monocopter that can fly in singular or cooperative configuration. You can attach two of them together magnetically to have them fly together in cooperative mode. As the researchers explain, these Modular Single Actuator Monocopters (M-SAM) have connectors that “allow for passive separation of the units without the need for a dedicated separating actuator, by harnessing the variable centrifugal force from controlled adjustment of the rotating speed of the craft.”
The above video shows these single actuator monocopter in action. More information is available here.
[Authors – Xinyu Cai, Shane Kyi Hla Win, Luke Soe Thura Win, Danial Sufiyan, Shaohui Foong]