How can I make a file hidden on Windows?

If you don't want/don't have access to win32 modules you can still call attrib:

import subprocess
subprocess.check_call(["attrib","+H","myfile.txt"])

If this is for Windows only:

import win32con, win32api

file = 'myfile.txt' #or full path if not in same directory

win32api.SetFileAttributes(file,win32con.FILE_ATTRIBUTE_HIDDEN)