A .bat file that contains the console command ‘player.placeatme c1aeb’
This places a workshop at the player’s location and once placed the current cell becomes activated as a ‘settlement’ allowing you to build, scrap and all the other things you normally would.
Quick word of warning, you can disable the workshop in the console afterwards but the cell stays flagged. Meaning it will always be a settlement from that point on. Haven’t run into any unforeseen consequences but I am sure they are some. So I wouldn’t scrap everything and then build some crazy kowloon walled city if you aren’t prepared for the possibility something might break.
Have not tried it on an interior cell.
You must first toggle god mode to open the settlement menu.
To install, simply extract the file to your Fallout 4 folder. In game, open your console and type ‘bat settle’. Toggle god mode. Build, scrap and enjoy.