Use Tkinter:
https://stackoverflow.com/a/4203897/2804197
try:
from Tkinter import Tk
except ImportError:
from tkinter import Tk
r = Tk()
r.withdraw()
r.clipboard_clear()
r.clipboard_append('i can has clipboardz?')
r.update() # now it stays on the clipboard after the window is closed
r.destroy()
(Original author: https://stackoverflow.com/users/449571/atomizer)