External Extension Library Help

Hi Everyone,
I had posed this question about a month ago but didn't get any responses.
How do I go about setting up an external library specific to our product
catalogs attributes? I need a much more granular library than what
schema.org offer with it's generic (by design) item types.

This is the most detail I can find around the topic on the schema.org site:

External Extensions

Sometimes there might be a need for a third party (such as an app
developer) to create extensions specific to their application. For example,
Pinterest might want to extend the schema.org concept of ‘Sharing’ with
‘Pinning’. In such a case, they can create schema.pinterest.com and put up
their extensions, specifying how it links with core schema.org. We will
refer to these as external extensions.

There are also cases where a third party might want to host a broadly
applicable extension themselves. In such cases, the extension may go
through the kind of feedback process that reviewed extensions go through,
but can be hosted on the third party's site.

I really need some help with this as I am changing roles and will need to
hand off this project in the near future. Any help or guidance is
incredibly appreciated.

Thanks.
Russell

-- 
Russell Pruitt

The creative thinker is flexible and adaptable and prepared to rearrange
his thinking.
- A.J. Cropley