To instantly finish a gigastructure currently under construction: finish_megastructures
If it fails, use debugtooltip on an existing Systemcraft to copy its ship design ID, then add_ship <ID> . stellaris gigastructural engineering console commands link
Gigastructural Engineering is a massive mod (literally 10,000+ lines of code). then add_ship <
To give yourself a megastructure instantly, use the own command. You must have a construction ship selected to build it, or simply use the command to spawn it at your cursor (depending on structure type). stellaris gigastructural engineering console commands link