This summer I developed a Python package to generate UFO3 instance fonts from a multiple-master .vfb font file within Windows FontLab 5.2. It is available at https://github.com/spiratype/vfb_ufo3
. Most of the package modules are extension modules which have been compiled using Cython. Using the compiled extension modules speeds up UFO creation considerably.
I have not yet created a PyPi package for install using pip. Instead, create a 'vfb_ufo3' folder in your 'Lib/site-packages' directory and add the .py and .pyd files from the repo.
I created it primarily due to my own font production workflow for which I use 10,000 UPM instead of 1000. I have not tested (nor was it created for) building individual UFO fonts from single-layer .vfb fonts.
Please see the __init__.py docstring or the readme for documentation on using the package. If anyone finds any issues in using the module, please contact me here or raise an issue on the GitHub repo.