The ring is a little counterintuitive due to how different constituent rings expand or limit its mod set. There are 27 major variants that are all listed in this spreadsheet: https://docs.google.com/spreadsheets/d/1NxwolAPS6ZZoJGXlB6yCy5c4btACvNJVU91rC0E0EAM/
The most user-friendly way to implement it would be to let the user pick a Valley, Meadow, and Mountain they want to use, and present the mod pool based on that. Picking enabled mods and resolving mod conflicts can be done the same way as when crafting a new item.
Listing all possible mod combinations as separate variants (even internally) is unreasonable; the number is stupidly high. Likely better to only consider the 27 constituent ring combinations as "variants" and treat it as a craftable item with its own specific mod set.
Further discussion here: https://www.reddit.com/r/pathofexile/comments/dh1bae/precursors_emblem_research_spreadsheet_what_rings/
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