To build Panda with Python 3, just install Python 3 on your system (choose “install for this user only”) and then copy it into the win-python or win-python-x64 directory. Might want to copy python.exe to ppython.exe and pythonw.exe to ppythonw.exe so that you get the familiar “ppython.exe”. Then build panda3d the usual way, running something like:
makepanda/makepanda.bat --everything --installer --no-eigenAlternatively, you can use this semi-recent build I uploaded on April 13th 2015.
rdb.name/Panda3D-1.9.0-py3.4-x64.exe
When installing the Panda3D SDK, if the installer detects a compatible existing installation of Python, it will ask you whether it should plop a .pth file in the site-packages dir of that installation so that you can use Panda3D with that Python installation.