Looking at several "Tello Swarming" and "Tello Formation" videos and going through some earlier discussions, I thought about how to get more out of these little gems. After some soldering and programming, this is my take on drone formations:
My software also allows "free style" paths like Lissajous figures by implementing a closed loop using feedback from current position and a PID controller to allocate velocity to each drone in order to follow the path.
One of the big challenges was, to dose the light to the minimum for a better light show experience but to still give enough information to the VPS for position control.
Unfortunately, the position of the recording camera was too much aligned to the height of the drones, so that you loose the offset in depth. So there is still enough room for improvements...