I've found a bug in my last game where I donated my UEF engineering stations to somebody else. The flying drones dropped, and left piles of 203 mass each. However, the other player i donated the stations to had received new, free drones (but when they actually die they cost mass to "remake").
So you can basically get infinite mass by just gifting the stations to your teammate, reclaiming the wrecks and he'll just give the stations back, reclaim more wrecks and so on..