In the fountain pen community, they’re called frankenpens. Pieced from pens that otherwise would have rested in peace, frankenpens are the inevitable creations of mad people who wince at the thought of handling a ballpen.
My first (and only) frankenpen is a Parker 61 put together from three Parker 61s. It has a turquoise section, a teal body and a rainbow cap. The capillary filler works. The nib is a fat fine with a hint of tooth, just a hint when I rotate the nib to the right.
What is it about us, that we cannot leave well enough alone?