Yes this is alpha and yes the devs should be concentrating on making the core features actually work, but that doesn't mean we can't open the floodgates on our brains, right?
(my control panel broke ten years ago).
Anyway, here's what I was thinking:
Dyson spheres, rings and shells.
Matrioshka brains.
Giant spaceships (multikilometre)
What'll they do? No idea! Maybe you have one.
The giant spaceships just be a reskinned asteroid but with a few special effects such as:
Pretty coloured, irradiating explosions upon impact.
Introducing life to a planet.
random terraformation.
No I'm not drunk. This may just be reskins but it's a hell of a lot cooler than soccer balls, so there's that, if anything.