Spin-off coming from this thread:
@IvanDobsky, I am using Windows 10.
What I am curious about and interested in, would it be possible to have both installations using the same plugin, but with different settings?
If not, perhaps it would be possible to have a copy of the plugin and name it slightly different?
One for installation A, and the other for installation B?
Iāll copy and pasta my reply from over there as I canāt see how to move itā¦
THIS IS NOT A NOOBIE SAFE ZONE. DRAGONS LIVE BELOW THIS LINE. NOOBIES WILL BE SAFER STAYING AWAY. AS WELL AS ANYONE SCARED OF DIVING INTO %APPDATA% OR TEXT FILESā¦
This idea will allow you to have two different shortcuts sitting on your desktop. One would start Picard in configuration A and the other would start Picard in configuration B.
This means you can have ClassicalPicard.ini, PopMusicPicard.ini, Picard.ini sitting in the same folder together. Then depending on which Shortcut you use to start Picard it will pick a different ini.
This gives you some of your choices of āportableā while working with the installed edition.
Or more specifically - this gives you a Multi-Profile edition of Picard on a single PC where it can share plugins that have been installed in their fixed default locations.
Iāll go make you a win10 example as this is easier than you realise. 
Edit : Not having any luck at finding any documentation on the Command Line options. Iāll keep hunting, but it shows the lack of dev time available as there are a lot of features like this that are explained only in some obscure forum postā¦ but you have sent me on the hunt now. 
Edit: Stubbornā¦ have now found it. Have to use Picard -h to get the list.
usage: picard [-h] [-c CONFIG_FILE] [-d] [-N] [-P] [-v] [-V] [FILE [FILE ...]]
Soā¦ here is an example swapping ini files. Do you know about editing Shortcuts? I just have to experiment a bit first to check if the full path is needed or notā¦
This post will mutate again shortly with the answerā¦
-=-=- The Part Worth Reading Starts Here -=-=-
The CONFIG_FILE needs to be a full path otherwise it will assume it is sitting next to Picard.exe
In my example test I located the NORMAL picard.ini in the %APPDATA%\Musicbrainz\ folder and made a COPY of it and renamed the COPY to ClassicalPicard.ini (DONāT put a space in the name)
So they are both sitting side by side
Make yourself a Shortcut to Picard on your desktop. Maybe call it āClassical Picardā.
The Picard shortcut should look like this:
In the Target it says:
"C:\Program Files\MusicBrainz Picard\picard.exe" -c %APPDATA%\MusicBrainz\ClassicalPicard.ini
Notice how we have added the extras OUTSIDE of the speechmarks.
We use the -c to say we want an alternate ini file.
And then we give the full path to that file. In the example I used %APPDATA%\MusicBrainz\ClassicalPicard.ini
but I could also have used
C:\Users\Ivan\AppData\Roaming\MusicBrainz\ClassicalPicard.ini
This also means you can keep the ini files anywhere you like as long as you quote the correct paths.
Note1: If you run the ānormalā Picard that is already on your Start Menu \ Desktop \ wherever then that one will always default back to the standard Picard.ini file in its default location.
Note2: If, like me, you keep making typos in paths and Picard canāt find your named ini file then it will just make a new one with that name and store it where ever you pointed to.
Note3: A good way to test if things are working is to just resize the Picard window and close Picard. Your chosen ini file should now have a new āDate Modifiedā date coinciding with when you quit Picard.
Warningā¦ anyone who wants to keep their sanity might as well skip my next posts down there 
as the answer is all up here 
The rest is mad tangents and other theories.
That shouldnāt be a problem 
You are going fast and enthusiastic, but I will first create a fresh Acronis image of my finely-tuned system before I start experimenting with this. And that will be in a few days.
So no hurries on my account.
Cheers!
That is not so much a āsledge hammer and a nutā more like a āSteam Roller and a nutā!!
Seriously this cannot damage your PC. ALL that we are going to do is add a couple of shortcuts to your desktop. And they will select between two different text files that are sitting in the %APPDATA% folder.
Up to you thoughā¦ Solution is about to appear above in next few mins as I am just checking my results.
-=-=-
To refine this daft message of mineā¦ Backup is good idea. but the ONLY folders that will be affected at all here are:
C:\Program Files\MusicBrainz Picard\
C:\Users\hiccup\AppData\Roaming\MusicBrainz\
C:\Users\hiccup\AppData\Local\MusicBrainz\
So there is no need for a full roll back if things go FUBAR. Just the three folders named are the ones being messed around with. There is nothing in the registry of note anymore.
Itās not that.
I will also want to try it out with different settings for different plugins, different scripts, etc.
Itās time for me to create a recent complete image anyway, so thatās easier than to worry about what specific files and folders I need to back-up in relation to Picard and itās plugins.
(Damn, if only we had a portable install possible )
Now you are taking this off topicā¦ lolz. Get back into that other thread you slave driverā¦ how dare those Devs try and have a weekend off. 
First - look up and you will see your answer based on a standard installation.
Below this line will be dragonsā¦ but I told you I like to mess with things. These are thoughts expanding on that basic answer above.
BIGGER SCARIER DRAGONS HEREā¦ but easily tamed. Assuming you speak Welsh?
No one should try any of the below out without fifteen backups stored in different countriesā¦ Donāt blame me if it all explodes. Please claim on your Picard Warranty for a Full Refund.
Some of the problems of āportable installā is that Python will not be on most Windows PCs.
But just in messing with this there is a āalmost portableā option. No one is telling you that you MUST install in the default location. And once you are outside of Program Files you are more flexible with use.
I install in C:\MUSICTOOLS\MusicBrainz Picard\
As a test I renamed that folder - Picard didnāt care and launched. It even re-tweaked itās ini file and adjusted the path of fpcalc.exe. Picard is solidly written.
So take that further. Instead of the experimental ini files being in the hard to access %APPDATA% folder you could also put those alongside Picard. In fact, when you do that the command line shrinks to just
"D:\MUSICTOOLS\picard.exe" -c ClassicalPicard.ini
As long as the folder is outside of %PROGRAMFILES% you are free to put anything you like in there.
DRAGON WARNING:
The main confusion that will build up here is if you keep tweaking each ini file separately. You will have your default picard.ini in the normal %APPDATA% location, and these custom ones wherever you are storing them. But they will get out of synch with each other.
Learn to read them in notepad as they are only text files.
Reassurance is - if you TOTALLY screw it all up, just delete the ini files and a default one gets re-created. Which also shows that you wonāt need to do a full Acronis roll back - just keep your original picard.ini in case of problems. Then drop that āknown goodā copy back in the default location and all will be back to normal.
Right - that is enough hacking around for now. You may notice I enjoy puzzlesā¦ now I really should be cooking dinner. LOLz
Ask any questions you like and Iāll try and clear up anything I have said here. Obviously I am just reverse engineering so the RealDevsā¢ will be able to point at my suggestions and laugh\groan\scream that I am doing something wrong. But it is thanks to how well things are written that hacking like this can work.
Back to your initial question about plugins. Which plugin are you talking about? It depends on where that plugin stores its settings. If the settings are in picard.ini then there will be no problem. If that plugin stores its settings elsewhere then youāll need to give me clues as to what to look for. Or we may need to check with a plugin author.
Looking at the plugins folders they are all just filled with zip files with old dates. So that implies to me that these plugin zips should not include their settings in the same place. I would hope their settings are in picard.ini but we can soon find out.
It is a bit confusing that you split this thread as my hacking around reverse engineering \ testing here has now come back full circle. And it will be confusing to post this stuff back over there as it will be out of context.
Picard ALMOST works as a portable app already. I just stuffed itās folder onto a memory stick and then shoved that into another PC. And it started up fine. Clearly it can find its own Python in the sub folders. Clever Picard.
Soā¦ this means a little tweaking and you can have your portable app. It depends where you need to portable it toā¦ maybe the following will work
Copy the whole Picard folder to the stick. Make sure all the parts are in the same folder.
Copy your picard.ini file over to the same stick. Drop it NEXT TO picard.exe
Make a shortcut in the root of the stick that tells Picard to start with the local ini file. shortcut will be something like āpicard\Picard.exeā -c picard.ini (Okay - this donāt workā¦ needs to have the pesky drive letter in the short cutā¦)
Soā¦ all we need to ask the devs is - please can we have a variable that can be put into Picard.ini that will tell Picard where to find the plugins.
(Though it would not surprise me to find you can just call a folder āPluginsā and place it underneath the Picard folderā¦ Iāll test that soon - nope. That didnāt workā¦)
So the portable experiment is āclose, but no pluginsā. If there was a way for Picard to name the Plugin location in the ini file - and name it in a way that works as a relative path - then youād have your portable install on a memory stick.
If all you want to do is run from multiple different Picard ini files on the same PC, as a multi-profile Picard, then that DOES work as the plugins are in their fixed locations on that PC.
-=-=-
Yeahā¦ this thread has become the rantings of a loony as he chases some weird tangentā¦ so Iāll clean this up again another day to be more sane and less ramble through the researchā¦ but my theory always is āYou never know until you tryā
And ask questions. Iāll clear up anything here that does not make sense or is plain stoopid.
-=-=-
The TL;DR version? Just read my post with the pretty pictures in it. Ignore all the mad discovery postsā¦ unless you are curious about the journey of discovery here.
I think the easiest way to do this is really to have separate configs with the -c parameter as @IvanDobsky described above. All of Picardās configuration, including plugin settings and scripts, are stored in this ini file.
In regards to using different plugins this is also possible. While all your configs will use the same plugin installation location, you can activate different plugins with different settings per config.
I use the config file parameter a lot, especially for testing and development.
The two threads serve two different purposes.
The original one is strictly about the wish to have a portable Windows installation of Picard available.
Iām sure that request will come up once in a while, and the concept of portable programs is simple and well-understood by many.
Also, as I mentioned there, that would allow for testing beta releases without altering your stable running setup.
This thread was raised because you came up with the idea of having several configuration files, using the same full installation of Picard.
Today I had some time to give it a shot, andā¦
Brilliant!
Got it to work in only a few minutes, and it seems to work flawless, including different settings for shared plugins.
So thanks a lot @IvanDobsky!
(I wish I had this when I started out learning Picard and testing scripts and plugins)
Excellentā¦ 
Glad it works for you.
Plenty of credit needs to go to the devs for a good design that allows this.
Ah yes, a big thanks to the whole dev team and guys like @outsidecontext too!
This upgrade really made my computer universe a happier place today:
Bonus points for the funky icons
Come and get them while theyāre hot:
https://www.dropbox.com/s/nzym994b73odrz7/Picard%20icons.rar?dl=0