Building

Once you’ve created your skin’s CSS/USS files and assets, you need to build it to generate the modified bundle files that FM can use.

Build Process Overview

FM Skin Builder:

1. Scans FM’s original bundle files
2. Parses your CSS/USS and mapping configurations
3. Patches the bundles with your changes
4. Outputs modified bundles to your packages/ folder

Quick Reference

Build Output

After building, your project contains:

my-skin/
├── config.json
├── styles/
    ├── mapping.json
│   └── base.uss
└── packages/           # Build output
    └──  [modified bundles]

The packages/ folder contents go into FM’s skins directory.

Workflow

1. Edit - Make changes to CSS/assets
2. Preview - Quick validation (optional)
3. Build - Generate output files
4. Apply to Game - Copy to FMs installation directory
5. Launch game - Reload skin in FM
6. Restore Backup - Always restore backup before new build
7. Repeat - Iterate until satisfied