41 points
Well that’s assuming it’s completely solid and not hollow. Hollow would probably be pretty huge, although the structural rigidity might not be great. Maybe we make a giant obsidian 3D printer and print it at like 10-15% infill.
26 points
An obsidian 3d print is less crazy than you might think. It’s essentially rapidly cooled lava.
Need something to hold the lava, then pressurize it to squeeze it through a nozzle that that has attached cooling units.