Since version 2.2, developers can use the Meta Box Builder to export PHP code that can be used on another websites without the extension. You can use Meta Box Builder to prototype the custom fields to test. When everything works, you can export the PHP code to use to increase the website performance.
Besides, with this feature, you can also import and export the custom fields and custom meta boxes configuration to use in multiple sites.
We hope this feature will make your development life a little easier. If you haven't updated the extension to the latest version, please do it now.
We will keep improving the extension to be more user-friendly. Please let us know what you think and what you need in the comments.
How to Easily Copy Custom Fields From Sites to Sites with Meta Box Builder 
Meta Box Builder 3 - A Truly New Experience 
How to Export and Import Custom Fields with Meta Box Builder?