It has been shown during important events concerning Primo, Jakob and Lester, the usage of the Grand Design in the end is to enable the gigantic Divine Temple to descend upon New Domino City. Though not explicitly stated in the anime, it is possible that the Grand Design is a much larger version of the Infinity device created by the Momentum Express Development Organization, as it is in the shape of an infinity symbol, is powered by Ener-D, and is used to open a portal for the Arc Cradle.