Why build one at all? Jesus answered Dives who thought his brothers would be converted if someone rose from the dead... (Luke 16:31 NIV) "He said to him, 'If they do not listen to Moses and the Prophets, they will not be convinced even if someone rises from the dead.'" Do we really think people are going to be genuinely converted because of a replica of the ark? Use the money to spread the gospel, not a gimmick. Remember the lesson of the Gospel Blimp.