createGuiModel
fun createGuiModel(background: Boolean, stretched: Boolean, vararg layers: ResourcePath): ModelBuilder
Creates a new GUI model using the given layers as texture
With background, the model will have the vanilla inventory background.
With stretched, the model will be stretched to 18x18 pixels. Due to mip mapping, this requires a 32x32 texture with the actual texture placed at (0, 0) to (18, 18).