FYI: if you need to install a package for a specific python you can use pip3.6 install numpy

some additional info from @frederik: both RoboFont and DrawBot look at the sitepackages folder for the same Python version as the one embedded in the app currently Python 3.6 is embedded, so in Mojave one would have to install py3.6 in order to have RF access packages in 3.6/sitepackages… back to your question: How do I install site-packages in RF3 on Mojave, which comes with Python 3.7? if you don’t want to install py3.6, use the external_packages folder install Python 3.6, and then install custom libraries in 3.6/sitepackages

@frederik thanks a ton, it worked!

great news, it would be nice to give the beta version a test, so yes please, thanks a lot!