Headcanon: Erik learned by Emma Frost, in 1962, after First Class events, about Shaw helmet, that was build by metal, but have anti-telepathic tech, also the mirrors of nuclear reactor of submarine of Shaw. After he part way again with Xavier in 80s, in 90s, he returned to be Magneto, he then meets Forge, a intelligent mutant, like Beast, that sympathized with Magneto, so he decides to join the new Brotherhood (in Ultimate universe, he was part of Brotherhood), he didn't acted in field, like the others, he was the scientist of team, so Xavier never knew him, so Forge build the helmets to Magneto, by using the Cerebro's knowledge that Erik get, by helping Beast and Xavier to build Original Trilogy's Cerebro, the protections in Magneto's hideout in Genosha and Mutant Conversion Machine in X1. But, prior X1, Forge decides to betray Erik, change his mind about Magneto's philosophy, so he end up get killed off, that's why he is not with Brotherhood in X1. After X2, Magneto, Mystique and Pyro returned to Genosha. Between X2 and The Last Stand, they transported some of the anti-telepathic protection in Genosha to put in a new hideout, The Last Stand's Magneto hideout in the forest. This all just happened in Original Timeline.
Magneto is not a genius, like Beast or Forge, so, for me, he had help to build the subsequent helmets, the machine of X1, etc, this what I think.
This headcanon make sense? Contradict the canon of Fox movies? Could be canon? What do you guys think?