I am trying to export a Rigid Body from blender to a .bullet file using the python script using the following video as a guide:
https://www.youtube.com/watch?v=fv-Oq5oe8Nw
The weird thing is that sometimes the .bullet files are created but sometimes does not. Also in some other projects the .bullet file, never appears. Does anyone knows why?:/
I've written an add-on for Blender which automates exactly this task, and so far seems to work flawlessly. It's available on GitHub: https://github.com/V0idExp/blender-bullet-export
After having installed it via File -> User Preferences -> Add-ons window, select an object and invoke the exporter via File -> Export -> Bullet physics data (.bullet)