After configuring Paperclip to use S3 that appeared:
The specified bucket does not exist
Very easy to create Amazon S3 bucket with S3Fox plugin.
Error message:
The bucket you are attempting to access must be addressed using
the specified endpoint. Please send all future requests to this endpoint.
The probem was that "Currently the aws/s3 Ruby library doesn't handle European buckets at all". So create new bucklet NOT in Europe.
Have a nice day!