Used as a noun or suffix to describe something that is a fake, imitation, or resembles something else, often with a negative connotation of being inferior or deceptive. Common in compounds like まがい物 (imitation goods) or 芝居まがい (theatrical, melodramatic).
模造 refers to a reproduction or replica, often neutral or technical, whereas まがい carries a stronger nuance of being a poor or deceptive imitation.
Etymology
Derived from the verb 紛う (まがう, 'to be mistaken for'), with the continuative form まがい used as a noun. The kanji 紛 carries the meaning of 'confusion' or 'mixing up', reflecting the idea of something being mistaken for the real thing.