for i, item in enumerate(btn):
    ttk.Button(self.mainframe, text=item).grid(in_=self.mainframe, column=i,
        row=3)

def main():
    root = Tkinter.Tk()
root.columnconfigure(0, weight=1)
root.rowconfigure(0, weight=1)
makeGUI = MakeGUI(root)
root.mainloop()
if __name__ == '__main__':
    main()
Python & ttk Using labelFrames to clean up a frame