I was playing with my refraction code a little (nothing spectacular), and I found myself doing things like changing the refractive index of a material, then rendering, then changing again, then rendering, etc. So I'm going to make the whole thing scripted properly, so you can generate multiple output images. All that really needs is me to make a raytrace() function that the script can call, and reset_scene() and reset_lights() commands. Or I could be "clever" and give objects and lights handles that you can use to delete them with.

After that, it's just a case of scripting a loop to change some params slightly and raytrace.

Random picture from setting the refractive index of a sphere to 1.25, with 4 smaller spheres behind it: