I'll be as descriptive as possible... I have no way of taking screenshots cause my print screen key doesn't work.

THIS WILL NOT WORK AS AN ACCESSORY. You can take the tail from an accessory but the tail will have to be added to a costume. It's not that hard.

Create a work folder. It makes things much easier.

Move all files mentioned to said work folder.

You'll want to take a tail from somewhere. There's plenty of mods that adds tails. If you're using an x2m open the x2m in winrar and take out the files you need. Specifically the emm, emd, and esk. Make sure the esk is from the tail mod. if you use one from your game it won't have the required tail bones. I'm not going to explain naming since that's covered in eternity's tutorials.

Open whatever the tail is attached to be it a costume or an accessory and open it in blender. Be sure to drag both the skeleton that comes with the tail mod along with file that tail is in over emdfbx. Import the fbx to blender. I suggest using blender v2.74 as the newest version didn't work for me. 3dsmax would work as well I think.

If you're using an already made x2m open that x2m in winrar and drag the costume files into the work folder. Then edit from there.

Go to the materials and select everything but the tail and delete it. Then import another pant or bust file. HERE IS THE IMPORTANT PART: Make sure to change the material name of any tail to HAIR_tail. HAIR has to be capitalized. This tells the game its part of the hair. So whenever the hair changes color the tail will change color to match the hair. The only downside to this is that the tail will always match the hair color. Export to fbx and set forward option to Y Forward export. If you see a little icon next to the scale be sure to click that. 2.74 doesn't have that which is why I prefer it. I don't have 3dsmax so I don't know that one. Once its exported drag the exported fbx over fbxemd and you're done with the model.

Once you do that drag the emb file over embpack, not the dyt.emb, data000 in photoshop with dds tools, save flipped vertically. This fixes a texture issue that will crop up when adding or removing files from an existing model. it's cleaner to realign the textures but its annoying for me so I just save flipped vertically. Once you save it drag the entire folder over embpack and you're done.

Take the emm and drag it over genser or emmxml and open  it notepad++.

Change the tail entry to match the model entry. I'll include the entry I personally use. It doesn't matter what the emm is looking in the dyt.emb for. It can be assigned to anything since the game doesn't look there for hair color.

<EMMMaterial name="HAIR_tail" shader_name="TOON_UNIF_STAIN2_DFD">
       <EMMParameter name="MatCol0R" type="0" value="0.0" />
       <EMMParameter name="MatCol0G" type="0" value="0.0" />
       <EMMParameter name="MatCol0B" type="0" value="0.0" />
       <EMMParameter name="MatCol0A" type="0" value="1.0" />
       <EMMParameter name="MatCol1R" type="0" value="0.0" />
       <EMMParameter name="MatCol1G" type="0" value="0.0" />
       <EMMParameter name="MatCol1B" type="0" value="0.0" />
       <EMMParameter name="MatCol1A" type="0" value="1.0" />
       <EMMParameter name="MatCol3R" type="0" value="0.0" />
       <EMMParameter name="MatCol3G" type="0" value="0.0" />
       <EMMParameter name="MatCol3B" type="0" value="1.0" />
       <EMMParameter name="MatCol3A" type="0" value="1.0" />
       <EMMParameter name="MatScale0X" type="0" value="1.0" />
       <EMMParameter name="MatScale0Y" type="0" value="1.0" />
       <EMMParameter name="MatScale0Z" type="0" value="1.0" />
       <EMMParameter name="MatScale0W" type="0" value="0.0299999993" />
       <EMMParameter name="MatScale1X" type="0" value="0.0" />
       <EMMParameter name="MatScale1Y" type="0" value="1.0" />
       <EMMParameter name="MatScale1Z" type="0" value="1.0" />
       <EMMParameter name="MatScale1W" type="0" value="1.0" />
       <EMMParameter name="Glare" type="65537" value="1" />
   </EMMMaterial>
Copy that into your emm.xml file. Shouldn't need to change anything. Then drag the emm.xml over genser or emmxml.

Now that those two files are situated you'll have to do some editing in the costume creator and skill creator. If you're using someone elses mod I'll explain how to do this.

If you're not using someone elses mod then prep the costume files for the costume creator, make the costume, embed it in the skill and you're done. Basic stuff and all covered in eternity's tutorial.

If you ARE using someone elses mod then it's a little more complicated.

Open the skill x2m file in winrar, open the costume attachment folder, and drag the x2m inside to the work folder.

Once you do that open the costume attachment x2m in the costume creator, on the info tab generate a new guid and give it a new name, changing the guid isn't required if you are not planning on using the original skill. Go to the files tab and select the work folder. This folder must contain your edited emm and emd as well as the costume's emb and dyt.emb. DO NOT put your esk file in that folder. I'm going to include the an x2m you need. This x2m will have the female required files, you'll have to find the male files yourself. They're easy to find. Once you have selected the correct folder go to the bcs tab. On the bcs tab copy any of the entries and paste it under the pants entry. If the name model id isn't 10000 then change it to 10000 or whatever stage you're on. Save the x2m.

Open the skill you're editing in the skill creator and go to the bcs tab, select the costume x2m you just made and click embed. Then go to the transformation tab. This is very important. If you're using lazybone's mod then you HAVE to change the hair colors of God, Blue, Blue Kaioken, Blue Evolution, Rose and Mastered Ultra Instinct. If you don't change the colors of these stages the tail will end up being yellow in any of these stages. Once all that's done, you can generate a new guid if you want just to make it unique and not replace the original but its not required. Save and you should be done.

Ok. Click here to download my x2m with all the female files made. If you want to release a female mod with these files go ahead, just give me credit. If you want to add the male files then open that x2m in winrar and drag all the files to a different work folder. Then do the same with some other mod's tail files. Specifically SYM.ean, HUM.esk, and CMN.HUF.lby.ean. The first one is located in the folder SYM, second is in HUM and third is in CMN. All three folders are in the chara folder. The last one contains all the animations for conton city. If you don't have an edited lby.cmn file, when you're in conton city the tail will act like a stick. Once you have all the files under data/chara then open my TailFiles.x2m file in the costume creator and go to files, and go to the additional data and click the tail file work folder. The additional files entry is helpful if you want to make a replacer but have it an x2m.

That's all there is to it. Hope you guys make some awesome tail mods. As I said the tail color will match your hair color but this is by far the simplest way to do this.

I don't know if anyone has thought of this but it was just a theory I had and it works. I'd be surprised if no one thought of this, its so simple. Remember this will not work with an accessory. Least it didn't for me, but I'm bad at making accessories. Try for yourself.

If you need clarification on any part leave a reply and I'll do my best to help. As I said, this probably isn't the best for new modders since there's a lot of work involved. If you are a new modder and want some help I'll be happy to assist.

Sorry for no pictures but my print screen key has been broken for a while. I explained the best I could.

This should be obvious, but don't release someone else's work and call it as your own. In my experience the modding community is pretty chill and will give you permission if you ask. Anyway that's all. Hopefully it will help people.