Kotaku A post up at Slashfilm reveals that both the Sentinels from the past and future eras of the newest X-Men film went through a few different iterations. Design studio Framestore contributed to Days of Future Past and worked up radically different looks for the fearsome mechanical menaces that Wolverine and crew have to take on. Some of the looks invoke Japanese mecha styling. Others look a lot more amorphous and organic, with a slightly feminine silhouette that recalls X-Men arch-villain Mystique.
IMO Singer should have gone with the mecha style Sentinels on the top right and keep the fem-Sentinel to be his Nimrod. But what the fuck do I know?! I've only been a comic book fan since I first learned how to read and wanted to pursue a career in comic books as a young adult!!!