This service is for people who need more functionality than the free Firefox MSI packages (more info). You start by choosing a Firefox version, and a language.  Then customize options like the name and icon.  Upload your own extension or add from the Mozilla Addon Repository.  You can also upload your own company server certificates. Press the build button and in a few minutes you can download your customized package ready for deployment.

Picking version and language

General options

Certificates

Autoconfig

Extensions