slither.io has a feature called "Build a Slither", where the player can create their own custom skin to suit their wishes. Since its creation, it has become immensely popular, and many players have created their own unique skins to identify themselves. There are 38 different segments available (not hidden). 3 of them have stars. A custom skin must have between 1 and 47 segments. This means that there are a total of around 1.8256 × 1074 custom skins. Note that this includes duplicates, such as black-white and black-white-black-white. For some reason the snake appears to keep on shrinking when selecting a skin, so you may not be able to see all 47 segments.
All segments can be used in Build a Slither except for Segments 36 (UK flag), 38 (dark blue) and 40 (blank).
Build a Slither sets snake.rcv to 0, meaning that after saving a custom skin, pressing the right arrow gives you the Indigo-Blue Skin. It is impossible to recreate any official skin with Build a Slither, as it sets cusk to true, while all official skins have cusk set to false. This means that Build a Slither skins lack the striped pattern of official skins.
- ↑ It's not really Skin 0. setSkin(snake,0) gives the Lavender-Purple Skin.