I don't know the correct way to do it, but this manual method is the approach I've used for simple scripts which seems to have preformed suitably.
I'll assume that whatever directory I'm in, the Python files for my program are in the relative src/
directory, and that the file I want to execute (which has the proper shebang and execute permissions) is named main.py
.
$ mkdir -p MyApplication.app/Contents/MacOS
$ mv src/* MyApplication.app/Contents/MacOS
$ cd MyApplication.app/Contents/MacOS
$ mv main.py MyApplication
At this point we have an application bundle which, as far as I know, should work on any Mac OS system with Python installed (which I think it has by default). It doesn't have an icon or anything, that requires adding some more metadata to the package which is unnecessary for my purposes and I'm not familiar with.
To create the drag-and-drop installer is quite simple. Use Disk Utility to create a New Disk Image of approximately the size you require to store your application. Open it up, copy your application and an alias of /Applications
to the drive, then use View Options to position them as you want.
The drag-and-drop message is just a background of the disk image, which you can also specify in View Options. I haven't done it before, but I'd assume that after you whip up an image in your editor of choice you could copy it over, set it as the background and then use chflags hidden
to prevent it from cluttering up your nice window.
I know these aren't the clearest, simplest or most detailed instructions out there, but I hope somebody may find them useful.