So, on google play there is this app called Skin Pack Maker. But it doesn't support 128x128 skins (possibly not yet?) But I have an easier solution. To do this, you need to use the following:

Notepad

Easy right? Very. So, to get started, I have made an outline. So, every skin pack has a skin.json and a manifest.json plus a folder called texts. The only file in there is named en_US.lang if its english. To start off, I will give you the code for each one and their titles labeled in bold.


Skins.json

{
"geometry": "skinpacks/skins.json",
"skins": [
{
"localization_name": "[your skin name]",
"geometry": "geometry.humanoid.custom",
"texture": "[your skin name].png",
"type": "free"
}
],
"serialize_name": "[your skin pack name]",
"localization_name": "[your skin pack name]"
}

Manifest.json

{
"header": {
"name": "[Your skin pack name]",
"description": "[Your description]",
"uuid": "d3a47bcb-1b4c-4be1-a626-cced7d9dfba2",
"version": [
1,
0,
0
]
},
"modules": [
{
"type": "skin_pack",
"uuid": "26d8f2df-2a8f-45b8-9ced-24e741310156",
"version": [
"[number]",
"[number]",
"[number]"
]
}
],
"format_version": 1
}


en_US.Lang

[skin name]=[skin name]
skinpack.[Pack name]=[skin pack name]

If you wanna make it so much easier on yourself for these codes, try this .json editor. I suggest you copy and paste your code onto notepad first, save it as [name].json and click and it drag it onto the site and it will generate it for you. If you want further help, check my profile for how to contact me!



NOTE: Everything I just highlighted in yellow when you input a name, make sure to remove the brackets on the begginning and end of each one. I have provided you an example below so you dont get stuck!


EXAMPLE:
Skins.json

{
"geometry": "skinpacks/skins.json",
"skins": [
{
"localization_name": "Sylvias_Example",
"geometry": "geometry.humanoid.custom",
"texture": "Sylvias_Example.png",
"type": "free"
}
],
"serialize_name": "Sylvias_Example",
"localization_name": "Sylvias_Example"
}

Manifest.json

{
"header": {
"name": "Sylvias_Example",
"description": "An example provided to you by yours truly :)",
"uuid": "d3a47bcb-1b4c-4be1-a626-cced7d9dfba2",
"version": [
1,
0,
0
]
},
"modules": [
{
"type": "skin_pack",
"uuid": "26d8f2df-2a8f-45b8-9ced-24e741310156",
"version": [
"[number]",
"[number]",
"[number]"
]
}
],
"format_version": 1
}


en_US.Lang

Sylvia=Sylvia
skinpack.Sylvias_Example=Sylvias_Example