3DMM: Successfully building 3D Movie Maker from source
After a few days of analysis, I finally got it to successfully build, albeit with some caveats. Some of the issues with the repository come down to just missing components, one of the notable ones being BRender itself. Another one that will become very apparent while building is the missing source code for the AudioMan. For the life of me, I couldn't find ANY information on it, so I had to clear out any code referencing the AudioMan library.
Dealing with BRender was easy, however, as the source code for BRender v1.1.2 had been released a few days ago which, as far as I can tell, is the closest to whatever version of BRender 3DMM used. I grabbed the libraries from the leaked SDK (as I still don't know how to build that one), and updated the code to work with BRender v1.1.2. (just had to replace the headers and update some of the callbacks)
Then I had to create my own batch file for setting up the environment. It's not too different from setvars.bat, other than setting MSVCNT_ROOT to where MSVC 2.2 is located and CHIP to IN_80386 (as it is required for some of the endianness-related code). I also directly set up the MSVC 2.2 environment variables from there.
The tools from the source root are unbuildable, as the headers they require are missing. Those headers could potentially be reconstructed if you're willing to analyze the source code for the tools.
The game plays just fine, however the audio mixing is entirely broken, and there are some visible graphical glitches.
UPDATE: The fork is here, but you might prefer 3DMMForever / Chocolate Socrates instead.
https://github.com/prettytofugirl/3DMM/