Download the Heroku backup that you want
Get list of backups
heroku pgbackups --app $APP
Get url for backup, and download
heroku pgbackups:url $backupId --app $APP
wget $theBackupUrl
Restore the backup to a db
createdb dbname
pg_restore -d dbname $dumpFile
change which db you are using
psql=> \c dbname
Then, to move that and clone it to a new db with a different name (connections to the cloned DB need to be stopped):
CREATE DATABASE $newDb WITH TEMPLATE $dbYouAreCopying OWNER $owner;
list your dbs to you can see that it worked
psql=> \l
To pull directly from Heroku:
heroku pg:pull HEROKU_POSTGRESQL_MAGENTA mylocaldb --app sushi