I followed these steps to run Python 3 on Sublime Text 3.
Select the menu Tools > Build > New Build System and I entered the following:
{ \"cmd\": [\
You need to provide the full path to python3, since Sublime Text does not read your ~/.bash_profile file. Open up Terminal, type which python3, and use that full path:
~/.bash_profile
which python3
{ "cmd": ["path/to/python3", "$file"], "selector": "source.python", "file_regex": "file \"(...*?)\", line ([0-9]+)" }