I know fault already made one for helm and shoulders, but the shoulders seemed hard to follow for me and this way seems easy, just like editing weapons/shields.
As you probably know, you will need My Warcraft Studio, you can download it here: http://www.curse-gaming.com/en/wow/download-10030.html
And you will also need http://www.goblinworkshop.com
to find your item codes.
To get started go to goblinworkshop, and search for your shoulders, in this guide i'll use scouting spaulders, so after you searched and found your item, click on it, if you look, you should see "Model & Texture:" if you look below you might see something like LShoulder_Leather_B_01, it will be the first one, that is the m2 file, to make it more visually clear, the words highlighted in the picture is the file you will later name xxx.m2, the second one next to it will always be .blp
highlight the first one you see, in this case LShoulder_Leather_B_01, and paste if somehwere like notepad, and put .m2 after it, so it should look like
next highlight the phrase after that, in this case Shoulder_Leather_B_01Black, paste that in your notepad, and put .blp after it, so your notepad should look like this
Now, open My Warcraft Studio, if you look at the top left of the window, you will see file, click on it, then click open MPQ archive
Find your world of warcraft data folder, and click on patch.mpq, and click open
A list of folders will appear, click on the folder ITEM, then OBJECTCOMPONENTS, then Shoulder
If you go down, you'll need to find your shoulder that you want to change into, in this case i'll change 'scouting spaulders' to 'nightslayer shoulders', so go down till you find LShoulder_Leather_RaidRogue_A_01.m2, that is the m2 file for nightslayer shoulders, right click on it, and go to "extract file to...", at this point, you need to create and item folder, so go to your world of warcraft data folder, and create a folder in there called "Item"
now inside the folder called "Item" make a folder called "ObjectComponents", be sure about capitals
open your "ObjectComponents" folder, and inside THAT folder, make a folder called, "Shoulder"
That is all the folders you shall need, so go back to my warcraft studio, and extract the left shoulder.m2 file into that shoulder folder you just created, so you shoulder folder should now look like this, depending on what shouler you extracted
now, back to my warcraft studio, scroll down till you find the right shoulder equivilant of nightslayer shoulder, or what ever shoulder you are doing, once you find it, right click it, extract it to your shoulder folder, your shoulder folder should now look like this, depending on what shoulders you choose
Remember the item codes you saved in your notepad folder, open those up again, ctrl copy the the m2 file you pasted, in this case LShoulder_Leather_B_01.m2, go to your shoulder folder, find your m2 file you made, right click, rename it, and rename it as the m2 in your notepad
now, rename the right shoulder, exept when you rename it, in this case instead of LShoulder_Leather_B_01.m2, it should be RShoulder_Leather_B_01.m2, replace the L with an R, the folder should now look like this, depending on what shoulder you chose
Now, go back to my warcraft studio, and in the shoulder folder there, scroll up and down until you find the .blp file for your shoulders, for nightslayer shoulders in this case it should look like this
right click the .blp file and extract it to your shoulder folder, which should look like this, depending on what shoulder you chose, you should have 2 .m2 files in there, and 1 .blp, AND dont forget to rename your .blp file to the one on goblinworkshop!
with all that, go back to my warcraft studio, and look at the top, and you should see pack, click on it, and click create MPQ archive
click yes you are sure you want to close the current archive, find your world of warcraft data folder, and name it 'speech2'
go back to my warcraft studio, back to pack at the top, this time click add file to archive, click on the "...", or browse folder, and go into your shoulder folder and find both your m2 files and your blp file, click any of them, but before you click ok, type this before it, Item\ObjectComponents\Shoulder\
so it should look like this
do that with all 3 files, till it looks like this
when you are done go to pack, and click "save and close archive", close everything, find your world of warcraft folder, open worldofwarcraft.exe, and be amazed, i hope this was easy to follow, was first guide so it wasn't that great. Good luck!
End result:
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