The Sitefinity Module Builder, released in Sitefinity 4.4, looks to be an incredibly promising module for building websites.
While it is released in 4.4 this is a first release of the module and I don't feel it will be quite ready for prime time until 4.5 or later.
There is currently no way to export a module from your test environment to your production environment.
We've been working with the module quite a bit the past couple of weeks though and we're exciting about using this in production soon.