Vozlov said:

The largest problem with Anakin building C3PO is the fact that in the OT we see multiple droids that are the same make as C3PO.

Which means that either Anakin Skywalker designed an entire type of droid that would be the pinnacle of protocol droids for decades, or that he was exaggerating when he said he built it, and in fact only put it together from spare parts of other protocol droids. That were conveniently lying around Tatooine and that were the pinnacle of protocol droids for decades.

wat.

He never said nor is it hinted that he designed 3PO. He rebuilt a protocol droid out of scrap he'd been smuggling out of Watto's junkyard.

That the 3PO model is old enough to be found in a junkyard is where I had issues with it.