Simon Verstraete covers creating HDAs in Houdini with this introduction.
This new multi-part tutorial from Simon Houdini (Simon Verstraete) covers an introductory look into what Houdini Digital Assets are and how they can help streamline your workflow. HDAs in Houdini can turn your node graph into a single custom node. It’s a great way to create custom tools within Houdini.
Verstraete shows how to create a simple chain asset that you can control by using an external curve. “Learn how to promote parameters and build a simple user interface for the tool.”