While constructing them naturally is the standard way, you can instantly spawn a structure around a selected object: create_megastructure [structure_id] .
| You Want This… | Type This Command (select a planet/system first) | | :--- | :--- | | (Galactic Core) | create_megastructure giga_birch_world_1 | | Matryoshka Brain (Star) | create_megastructure matryoshka_black_hole_1 | | Nicoll-Dyson Beam | create_megastructure nicoll_dyson_beam_1 | | Fusion Suppressor (Star) | create_megastructure fusion_suppressor_1 | | HRAE-MC (Research) | create_megastructure hrae_mc_1 | stellaris gigastructural engineering console commands link