Use s3cmd to batch set folder acl
Install
brew install s3cmd
Set acl
Make one file public
s3cmd setacl s3://spacename/file.txt --acl-public
Make all the files at a folder public recursively
s3cmd setacl s3://spacename/path/to/folder/ --acl-public --recursive
Make one file private
s3cmd setacl s3://spacename/file.txt --acl-private
Make all the files at a folder private recursively
s3cmd setacl s3://spacename/path/to/folder/ --acl-private --recursive