and one more thing, caps shield was not made as just a human experiment, it was mistakenly made when the scientist reaearchin the adamantium vibranium bonding left the both of em in his lab and went to sleep or somethin, when he woke up the other day, the two metals had somehow bonded into a disk like shape{this disk was later given to captain america who uses it as a shield}, however from then till now, the vibranium adamantium alloy has never been duplicated, and no one knows how the two metals bonded.