[Speculation Discussion] Our Primal

[Fantasia]

We don't know if they used the same method to seal Bahamut, Cid told us it was a machine and I would think the Garleans would have a better perspective of what it actually was because their technology is based on the Allagan Empire. A Machine or "The Twelve," could just be a different name for the same outcome.

I'd say it's incredibly likely that it was the same method of sealing him, since in the final video, during the imprisonment spell, The Twelve had starting constructing a planetary shell that looked EXACTLY like Dalamud did. If they used machines to seal him then it's strange that The Twelve's method resembled it so immensely.