You can easily add a new file to the config folder. This file should return configuration values. Check other config files for reference. Say constants.php is like so
<?php
return array(
'pagination' => array(
'items_per_page' => 10
),
);
You can now access this config file from anywhere by either using the Config Facade or the config() global function like so
Config::get('constants.pagination.items_per_page');
or
config('constants.pagination.items_per_page');
i.e.
config('file_name.variable_name');