I've finally gotten around to recording a demo of the current iteration of my tool to generate TripleO network isolation templates. You can watch the demo video (in which I say "umm". A lot. Sorry.) or check out the tool itself. There are also some templates generated with the tool if you want examples to start from.
The reasons for the tool's existence are covered in the video, but the summary is that networking is hard, and writing the network config for TripleO is too. The tool is intended to simplify the process by abstracting away some of the gory details of the config and providing some validation of the settings provided. As such, it's less flexible than a raw os-net-config configuration written by hand, but hopefully much easier and sufficient for the vast majority of configurations. I've used it successfully to create configs for real users on multiple occasions, and I've written several configurations for my development environments with it (they are linked above).
Also, it's not in tripleo-ui because it predates tripleo-ui by quite a bit, and it is intended to work with older versions of TripleO, all the way back to OSP director 7. It should be version-agnostic - the generated templates will work with all existing versions of TripleO (that's the intent anyway, if you find otherwise please let me know). There may also be some value for deployers who are using the CLI to do their deployment, but don't want to write their network config by hand.
Anyway, the tool has been around for quite a while now, but I'm not sure how many people knew about it prior to this. I'm hopeful it will be useful, but either way feel free to give me feedback through IRC or email. Thanks.