I vaguely remember one of the older animated series have one of the human characters build a mech so he can have a more active role in helping the Autobots but I cant remember which series it was. If anyone can help it would be much appreciated?

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Well it's not exactly one where he *BUILT* a mech, though my memory could be failing me, but in Transformers Cybertron, one of the human characters had essentially taken and repurposed a body from one of the insect like transformers on Cybertron, and turned it into a Mech suit.

there's also Transformers Prime, where the villain faction MECH actually made their own transformer to fight everyone for an episode.

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Well it's not exactly one where he *BUILT* a mech, though my memory could be failing me, but in Transformers Cybertron, one of the human characters had essentially taken and repurposed a body from one of the insect like transformers on Cybertron, and turned it into a Mech suit.

That's ringing a bunch of bells for me. I think that's the one I was looking for thanks.