I am creating a GUI for an application, modeled off of one I have seen. This other application uses diamond-shaped radiobutton indicators from Python Tkinter, and I can't seem to find out how to use a diamond-shaped radiobutton in my program. All of my attempts at creating a radiobutton result in a circular shaped radioubtton. And thoughts? I'm running my GUI on Redhat and Windows, same problem for both.
The forms toolkit offers precisely the components that it offers.  If you are not happy with round radio buttons, then code in OSF/Motif, which offers diamond-shaped radio buttons.  Either that, or you could hack the internals of the widget (sorry, "control": I am so accustomed to professional [= UNIX] terminology).  The round button is probably represented as a pixmap somewhere: just overwrite that in place, lickety-split, with your own two-tone pixmap that effects a rough diamond shape.
Diamond Shaped Radiobuttons in Python Tkinter