Total Internal Reflection test block

I created this simple test block as a test to measure and confirm total internal reflection in a clear print.

For my resin print, the print should be coated with a layer of resin after printing, drip-dried, then cured to achieve a glassy finish.

Faces for testing:

-The semicircle at the bottom allows radial light to hit the circle's centre (on the vertical flat surface) at any angle and test for the critical angle.

-Viewing from the vertical flat side, one can observe bright reflections from the semicircular surface. The slanted flat surface can be used as a mirror, reflecting light normal to the bottom out from the vertical flat surface and vice versa.

-Viewing straight into the slanted flat surface, the bottom and vertical surface act as the mirror and would reflect light normal and into the slanted surface back out.

Background:

Initially I noticed that post processing of clear resin prints can bring out a glass-like finish and upon observing total internal ref