Before proceeding, ensure you have both PostgreSQL and RabbitMQ installed and configured on your system. Verify that PostgreSQL is running and accessible, and ensure RabbitMQ is operating and that you can connect to it using your credentials.

Use Python to extract data from PostgreSQL. Start by installing the `psycopg2` library to connect to PostgreSQL. Write a Python script that connects to your PostgreSQL database, executes a query to fetch the desired data, and stores this data in a variable.

```python
import psycopg2

connection = psycopg2.connect(
dbname="your_db",
user="your_user",
password="your_password",
host="localhost"
)
cursor = connection.cursor()
cursor.execute("SELECT FROM your_table;")
data = cursor.fetchall()
connection.close()
```

Convert the extracted data into a format suitable for RabbitMQ messages. Typically, JSON is used for its lightweight nature and ease of use. You can use Python's `json` module to transform the data.

```python
import json

formatted_data = json.dumps(data)
```

Install the `pika` library to interact with RabbitMQ in Python. This library provides functionality to connect to RabbitMQ and publish messages.

```
pip install pika
```

Import `pika` in your script:

```python
import pika
```

Use `pika` to establish a connection to your RabbitMQ server. Set up a channel and declare a queue to ensure the messages have a destination.

```python
connection = pika.BlockingConnection(pika.ConnectionParameters('localhost'))
channel = connection.channel()
channel.queue_declare(queue='your_queue')
```

Send the formatted data to RabbitMQ using the channel's `basic_publish` method. Ensure you specify the correct queue name.

```python
channel.basic_publish(exchange='',
routing_key='your_queue',
body=formatted_data)
print("Data sent to RabbitMQ")
```

After sending the data, close the RabbitMQ connection cleanly to avoid resource leaks and ensure that all network buffers are flushed.

```python
connection.close()
```

This guide provides a basic framework for moving data from PostgreSQL to RabbitMQ using Python, without relying on third-party connectors. Adjust the scripts as needed to fit your specific data requirements and system configurations.