This is an updated tutorial on the Assign Shape Keys add-on that is bundled with Blender 2.8x versions.
Links of the add-on for curve tracing
Draw Tool: • Overview of Flexi Draw Bézier Tool | Free ...
Edit Tool: • Overview of Flexi Edit Bézier Tool | Free ...
Tracing Demo1: • Blender 2.8x Add-on - Demo of Flexi Bézier...
Tracing Demo2: • The Joy of Working with Bézier