As far as I know Tuhopuu is an experimental Blender version which tries to export directly to rib file renderers. If this is mistaken can anyone, please, give some brief information about what exactly is?
And… is it sufficiently stable in its present situation? If it is so -and if exists a version of it for Windows- where it can be downloaded from?
The tuhopuu version of blender is an experimental version where any new features/patches/code can be added much easier than into the actual Blender Foundation releases. This way there is always a stable full version branch of code and then a test version. Once a feature has been tested and or finished it can then be moved over to the actual Blender Foundation release branch. This is why the renderman export and other render export as well as many other changes in the code remain in the tuhopuu branch… they are not fully functioning. As linked above there are many people with their own version of blender compiled from the tuhopuu branch for testing of their own or other features.