Earlier tonight, I got a little tired of telling people that their plugin requests aren't possible in RMMZ because independent items aren't a thing yet, so I made a quick little patch to bring them into RMMZ.
What is an independent item?
Independent items (or weapons, or armors) were a feature of Yanfly's ItemCore plugin, where individual instances of items could be modified, through other plugins, without modifying all instances of that item. The ItemCore plugin itself had a random variance parameter that was the most obvious use of this, but there were several other plugins that built on this functionality to make specific items more unique, such as attachable augments, item upgrades, random prefixes/suffixes, and many others.
Since the current VisuStella ItemCore plugin does not contain this functionality, and it hasn't been in plugin waves 2 or 3, it's starting to look like this might be something we'll be waiting a long time for, so I took it upon myself to patch it into a working state in RMMZ.
First, this patch contains no YEP code. I do not have the rights to redistribute that code, and this plugin merely aliases some functions from it. It requires the YEP_ItemCore plugin to work.
Second, I haven't done much testing beyond opening some menus, equipping/unequipping items, and buying/selling them. I didn't find any crashes myself, but I didn't thoroughly test it, so I expect there might still be some hiding in there somewhere.
Third, this plugin doesn't really do much on its own. It removed the menu and window changes from ItemCore, such that the only things it changes are independent item related. The only way to see that it's even working is to note that independent items no longer stack in the item scene.
Fourth, ItemCore had inventory limits, which prevented you from buying more than one independent item at a time. The limit still exists, but the shop scene no longer checks for it, so you can buy multiple independent items at the same time now. I recommend setting it to an arbitrarily high number, because there is currently no way for the player to see or know there is a limit.
Fifth, make sure the 'Updated Scene_Item' plugin parameter in ItemCore is turned off.
This may allow some plugins for RMMV that required ItemCore to work in RMMZ again, but I ported this for my own use, so I cannot guarantee that. Most are probably still going to require a patch to work again, especially augments or item upgrades, as the modifications to the item scene were disabled in my patch.
Load Order:
For compatibility reasons, I recommend loading YEP_ItemCore before the tier 1 VS plugins, and then loading this patch directly after it in the load order, like this image:
Note, this was only tested with ItemCore version 1.30, but it should work with any newer version as well.
This patch is free for commercial and non-commercial use.
You do not need to give credit to use it.
You can redistribute it as you see fit.
You can modify it to add functionality or correct bugs, and share those modifications as long as the header remains intact.
You can download the patch from my itch.io page, or version 1.00 is attached to this thread.