Minimal Complete Machine

Current API Minecraft 1.21.1 / MBD2 21.1.1

This is the smallest loop KubeJS can create by itself. Use the editor for production states, models, Traits, UI, and multiblock Patterns.

1. Register the recipe type and base machine

// kubejs/startup_scripts/mbd2_registry.js
MBDRegistryEvents.recipeType(event => {
  event.createRecipeType('example:crusher')
})

MBDRegistryEvents.machine(event => {
  // The only registered builder keys are single and multiblock.
  event.create('single', 'example:crusher')
})

Restart the game. createRecipeType registers immediately; queued machine builders are built after all startup handlers finish.

2. Add a recipe

// kubejs/server_scripts/mbd2_recipes.js
ServerEvents.recipes(event => {
  event.recipes.example.crusher()
    .id('example:crusher/iron_dust')
    .duration(100)
    .priority(0)
    .inputItems('minecraft:raw_iron')
    .perTick(r => r.inputFE(40))
    .outputItems('2x minecraft:iron_ingot')
})

3. Add interaction diagnostics

// kubejs/server_scripts/mbd2_events.js
MBDMachineEvents.onUseWithoutItem('example:crusher', wrapper => {
  const machine = wrapper.event.machine
  wrapper.event.player.sendSystemMessage(
    Component.literal(`State: ${machine.machineStateName}`)
  )
})

KubeJS machine registration boundary

event.create('single', id) does not generate item/fluid/FE Traits, a Recipe UI, or a model. Finish the definition in the editor and keep the same stable ID for a production pack.