Begin by setting up a Python environment where you can write and execute scripts. Ensure that Python is installed on your system. You can use virtual environments to manage dependencies cleanly. Install necessary packages like `requests` for making HTTP requests and `elasticsearch` for interacting with Elasticsearch.

Use the PyPI JSON API to fetch data. You can use the `requests` library to send HTTP GET requests to retrieve package information. For example, to get data for a specific package, send a request to `https://pypi.org/pypi/{package_name}/json`. Parse the JSON response to extract relevant data fields that you plan to index into Elasticsearch.

Once you have the data from PyPI, transform it into a format suitable for Elasticsearch. This involves creating a dictionary for each document you want to index, mapping the PyPI fields to your desired Elasticsearch fields. Ensure that the data types are compatible with Elasticsearch, such as converting date strings to proper date formats.

Install and start an Elasticsearch instance if you haven’t already. You can download it from the official Elasticsearch website and follow the installation instructions for your operating system. Once installed, start the Elasticsearch service. You can interact with Elasticsearch via its RESTful API or using the `elasticsearch-py` Python library.

Create an index in Elasticsearch where you will store the PyPI data. You can use the `elasticsearch` Python client to define an index with appropriate mappings that mirror the structure of your transformed data. This step ensures that your data is stored efficiently and is searchable.

Use a loop to iterate over each data entry from PyPI that you transformed in Step 3. For each entry, send an indexing request to Elasticsearch using the `elasticsearch` client. Make sure to handle any exceptions and errors, such as connection issues or data formatting errors, to ensure robust data ingestion.

After indexing, verify that the data has been successfully ingested into Elasticsearch. You can perform a simple search query using the Elasticsearch API or the `elasticsearch` Python client to retrieve some documents from your index. Check that the data fields are correctly indexed and that the data types match your expectations.

By following these steps, you will have transferred data from PyPI to an Elasticsearch destination without using third-party connectors or integrations.