Hopefully in the story, or sidequest, or a dlc I don't care which we get to find out who built the exo. Maybe a counter force anpgainst the Vex? A weaponized ghost companion? Souls of those returned from the void?
The Cylons were created by man. They were created to make life easier on the Twelve Colonies. ...and then the day came when the Cylons decided to kill their masters.