How does the game handle background colors for items?

The game has a built-in enum called BackgroundType, which sits in the CraftData class. The possible values for this enum are listed below.

public enum BackgroundType
{
    Normal,
    Blueprint,
    PlantWater,
    PlantWaterSeed,
    PlantAir,
    PlantAirSeed,
    ExosuitArm
}

How can I create a custom background type?

To create a new custom background type, you will need to register an image as the background for some BackgroundType instance.

Fortunately, the custom enums system has made this step really simple. All you will have to do is name your brand new BackgroundType instance, then register an image for it.

private void Awake()
{
    var myCustomBackground = EnumHandler.AddEntry<CraftData.BackgroundType>("CustomBackground")
            .WithBackground(ImageUtils.LoadSpriteFromFile(pathToImage));
}

And that's it. Now you can use the new CraftData.BackgroundType instance anywhere you want.

How can I change an item's background?

To edit an item's background type, you need to call the CraftDataHandler.SetBackgroundType method sitting in the Nautilus.Handlers namespace

Examples

The following example demonstrates the usage of SetBackgroundType That makes the titanium background color green.

CraftDataHandler.SetBackgroundType(TechType.Titanium, CraftData.BackgroundType.PlantAirSeed);

Similarly, if we wanted to set the titanium's background to our custom background from earlier, it would look like the following:

CraftDataHandler.SetBackgroundType(TechType.Titanium, myCustomBackground);