1. Generate your API Key PRO

Before connecting Home Assistant, you need a secret key for communication.

• Log into 3D Print Manager.
• Open Settings (gear icon in the menu).
• Find the API Access section and click Generate New API Key.
• Copy the generated key (you will need it in Step 3).

2. Copy your Printer ID

The app needs to know exactly which printer the data is coming from.

• In 3D Print Manager, open the Manage Printers tool.
• Next to your printer's name, click the fingerprint icon ().
• You have now copied the unique Printer ID to your clipboard. Save it for later.

3. Add commands to configuration.yaml

Open your Home Assistant configuration.yaml file and add the following rest_command block.

Important: Replace <YOUR_API_KEY> with the key you generated in Step 1!

rest_command:
  # Command to start the print
  3dpm_start_print:
    url: "https://3dprintmanager.eu/api.php?key=<YOUR_API_KEY>&action=start_print"
    method: POST
    headers:
      content_type: 'application/json'
    payload: >-
      {
        "printer_id": "{{ printer_id }}",
        "job_name": "{{ job_name | replace('\"', '\\\"') }}",
        "duration_minutes": {{ duration | int(0) }},
        "mapping": {{ mapping | default('[]') }}
      }

  # Command to finish the print
  3dpm_finish_print:
    url: "https://3dprintmanager.eu/api.php?key=<YOUR_API_KEY>&action=finish_print"
    method: POST
    headers:
      content_type: 'application/json'
    payload: >-
      {
        "printer_id": "{{ printer_id }}",
        "slot": {{ slot | int(-1) }},
        "amount_used": {{ amount | float(0) }},
        "hours": {{ hours | float(0) }}
      }

  3dpm_fail_print:
    url: "https://3dprintmanager.eu/api.php?key=<YOUR_API_KEY>&action=fail_print"
    method: POST
    headers:
      content_type: 'application/json'
    payload: >-
      {
        "printer_id": "{{ printer_id }}",
        "progress": {{ progress | float(-1) }}
      }

Save the file and restart Home Assistant (or Reload REST entities).

4. Add Automations

Now you need to tell Home Assistant when to call these commands. Create two new automations in YAML mode.

Adjust 2 things:
1. Replace your_printer_name with the actual entity ID of your printer.
2. Replace <YOUR_PRINTER_ID> with the ID from Step 2.

Automation 1: Start Print

alias: "3DPM: Start Print"
description: Sends the exact time and filament mapping to 3D Print Manager
triggers:
  - entity_id: sensor.your_printer_name_print_status
    to: running
    trigger: state
actions:
  - wait_template: >-
      {{ state_attr('sensor.your_printer_name_active_tray', 'tray_index') | int(-1) >= 0 }}
    timeout: "00:05:00"
    continue_on_timeout: true
  - delay: "00:00:05"
  - data:
      printer_id: "<YOUR_PRINTER_ID>"
      job_name: "{{ states('sensor.your_printer_name_gcode_file') }}"
      duration: >-
        {{ (states('sensor.your_printer_name_remaining_time') | float(0) * 60) | round(0) }}
      mapping: >-
        {% set tray = state_attr('sensor.your_printer_name_active_tray', 'tray_index') | int(-1) %}  
        {% set slot = 0 if tray in [254, -1] else tray + 1 %}  
        {% set weight = states('sensor.your_printer_name_print_weight') | replace('g', '') | trim | float(0) | round(2) %}  
        [{"slot": {{ slot }}, "weight": {{ weight }}}]
    action: rest_command.3dpm_start_print
mode: single

Automation 2: Finish Print

alias: "3DPM: Finish Print"
description: Deducts grams from the spool and logs operating hours
triggers:
  - entity_id: sensor.your_printer_name_print_status
    to: finish
    trigger: state
actions:
  - data:
      printer_id: "<YOUR_PRINTER_ID>"
      slot: >-
        {% set tray = state_attr('sensor.your_printer_name_active_tray', 'tray_index') | int(-1) %}
        {{ 0 if tray in [254, -1] else tray + 1 }}
      amount: >-
        {{ states('sensor.your_printer_name_print_weight') | replace('g', '') | trim | float(0) | round(2) }}
      hours: 0
    action: rest_command.3dpm_finish_print
mode: single

Automation 2b: Failed or Cancelled Print

A print you stop on the printer, or one that fails, arrives as failed. 3D Print Manager gives back the filament that was not printed, using the progress the printer reported.

alias: "3DPM: Failed or Cancelled Print"
description: Returns unused filament to the spool when a print is cancelled or fails
triggers:
  - entity_id: sensor.your_printer_name_print_status
    to: failed
    trigger: state
actions:
  - data:
      printer_id: "<YOUR_PRINTER_ID>"
      progress: "{{ states('sensor.your_printer_name_print_progress') | float(-1) }}"
    action: rest_command.3dpm_fail_print
mode: single

How to handle Multi-Color prints?