Hey man, props for this tool! I was searching for something similar for quite some time now, and have just stumbled upon it here by accident.
The thing I also like about it is that you can insert your own custom icons. For those who are wondering how to do that, you extract the .zip file, go to "..\system\media\theme\miui_mod_icons\" folder, create your own 192x192 .png cutout image / icon in Photoshop or similar tool, and name that image with the Android package name (or Google Play ID) of the app you want to change icon of (for example, Google Chrome is com.android.chrome). You can find that for each app by going to app's Google Play Store link, and then reading the part after ?id=, or by using some 3rd party app such as AIDA64). Then you place the icons inside that folder, create .zip again, flash that and voila.
I wanted to ask you something tho. As you probably know, xiaomi.eu ROM comes with his own set of added 3rd party app icons, some of which are pretty nice and I got used to them. What I tried to use your tool for is to replace only the icons I want, so I tried to remove all of the icons from that folder I didn't want changed, and left only those I want to change, hoping that all the rest of the icons that don't have their source inside miui_mod_icons folder would stay intact and keep using those icons that came with xiaomi.eu. However, 3rd party app icons were completely removed and were using white background cutout. After that I tried to see what would happen if I remove default icon file located at "..\system\media\theme\default\", and then flash it, and after that background wasn't white anymore, but was the default gradient colored one that follows the icon tone.
So this basically I'm interested how to leave some icons from xiaomi.eu, and also insert some of my own. I managed to do the second one, but am still curious about the method how to do the first one, so it comes down to these questions:
1. Is there a way to replace only the icons with those found inside miui_mod_icons folder, and leave the existing ones intact (so that you have the existing xiaomi.eu custom app icon, instead of removing it altogether and having default icon with white background)?
2. If not, is there a way or some existing script with which you can change each individual icon (so not all of them, but only the ones I want, by placing desired icons inside some folder, and then zipping it and flashing zip file)?
3. If not, is there a way to extract custom 3rd party app icons that are inside xiaomi.eu ROM, so I can place some of them inside your miui_mod_icons folder?
Cheers and thanks again for this great tool and all your effort, having such a huge base of 13.000+ icons is really admirable.