It seems that the B3D (Blitz3D) to OBJ (3D object) conversion is possible with several dedicated 3D modeling and viewing programs. Not all data may be converted successfully though, in some cases only one layer of the graphics will be exported.
Convert Blitz3D/Max/Plus texture, mesh file to 3D object graphics.
We have found 4 software records in our database eligible for .b3d to .obj file format conversion.
Microsoft Windows software - convert b3d to obj on Windows
A graphics design tool for making 3D landscaping and animations
Convert from b3d file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned b3d to obj. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
Apple macOS / Mac OS X software - convert b3d to obj on OS X
A Mac version of the popular 3D visualisation software
3D modeling and animation package for Mac.
On-line services software - convert b3d to obj on web
A free online 3D model conversion service