Reading glTF extras (e.g. from Blender custom properties) to X3D metadata, support changing shape collision mode from Blender, documentation improvements - News - Castle Game Engine Forum
SOLVED] Blender Custom Properties and JME User Data - import-assets - jMonkeyEngine Hub
I figured out how to use custom properties in shaders and the compositor (Shader AOV). Here's a quick cheat-sheet to get you started. : r/blenderTutorials
Depsgraph updates and basic uuid support using custom properties - Python API - Developer Forum
ArtStation - Speed Up Your Workflow with Custom Properties in Blender!