repo2docker is the tool that is used to build the images on mybinder.org. The philosophy behind its design is to reuse files that people already place in their repositories anyway. To keep the effort for making your repository reproducible as small as possible.
Now there are a lot of repositories that run on mybinder.org, which means you could also run them locally with repo2docker. This means that a great way to get started with a new project is to copy an existing repo in that area and use their setup for repo2docker to get a nice environment that is ready to go.
If there was going to be a GUI for repo2docker, what would it look like? Would it be useful to integrate with nteract.io?
Maybe a different way of asking this question is: is anyone actually using repo2docker locally?