So yesterday I decided to take a try on your request and here it its:
Rough, and not diamond shaped but here it is:

Link to the post:
https://steemit.com/steemit/@ilhicas/search-author-content-categories-request-by-papa-pepper-or-a-tool-in-development

Direct Link to site to search authors content by tag:
http://ec2-54-186-245-209.us-west-2.compute.amazonaws.com:5000/

Will also do a shameless upvote on this comment, to gain some visibility so people can leave their opinions on other ideas they might have, as it seems I might be late to the party. But I work full time as a developer and don't really have that much time for personal projects, and hence why only today was I able to deploy it.