That's actually a pretty cool idea! I'm envisioning cubes about 10 cm on a side that can lift perhaps 100 grams to 1 kg, with magnetic latching (maybe solenoids

That's actually a pretty cool idea! I'm envisioning cubes about 10 cm on a side that can lift perhaps 100 grams to 1 kg, with magnetic latching (maybe solenoids controlling stronger latches) so they can self-organize into larger platforms. They'd use ultracapacitors with roughly a 1 second recharge time. So they'd constantly travel from the base station to the swarm, picking up energy and depositing it to the others. They'd form a platform that can lift appreciable amounts of weight, maybe even 100 kg (a person), and fly forever. Right now I think drones like that would cost around $100 each. But if they could be made for $10, then conservatively we could have flying platforms for around $10,000. And unlike batteries, the capacitors would last forever. Not so much grey goo, more like grey girders. I haven't researched this at all yet, if it already exists.