Python: Sprite Sheet Generator
Not in any specific program. Just a python script that take selected images and combines them as a sprite sheet.
Blender: Mixamo to Blender Naming convention
Blender's naming conventions for left and right bones is very strict, and Mixamo's does not fit within it. This means imported rigs from Mixamo will not have weights and bones edited symmetrically.
Blender has some nice find and replace features for mass renaming, but it'd be nice to automate for working in Blender, and on export change it back to Mixamo for import into Unreal.
I ran out of time to do this.