Here’s what the Flux documentation says about creating custom footprints:

"Create professional footprints that match your team's requirements and design specifications.

Overview

In this tutorial, we'll cover how to work with the PCB Editor to create custom footprints for your components. Whether you're designing a footprint from scratch or modifying an imported footprint, these techniques will help you create accurate, manufacturable component layouts.

Footprints define the physical layout of components on your PCB, including pad sizes, shapes, positions, and silkscreen markings. Creating precise footprints is essential for successful PCB manufacturing and assembly.

Adding Pads

The first step in creating a footprint is adding pads for component pins or leads. Pads are the copper areas where component pins make electrical contact with the PCB."

"Silkscreen markings help identify component orientation and boundaries during assembly. To add silkscreen elements: Adding Silkscreen Lines

Click on the "Objects" tab in the left panel Right-click on the footprint, hover over "Add", and select "Silk line" Add the Shape Start and Shape End rules to the silk line Enter the desired x and y position values for each endpoint

You can also drag endpoints or rotate lines (Right-click → Rotate)

Repeat to create an outline of your component

Adding Text Labels

Click on the "Objects" tab in the left panel Right-click on the footprint, hover over "Add", and select "Text" Add the Content rule to the text node Enter the desired text (e.g., component reference, pin 1 indicator) Position the text appropriately"