system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What makes Glass and some types of Plastic clear? Why couldn't we make clear metal or other "clear" Materials?
gpt
The structure of the atoms/molecules forms a pattern that lets light through, usually by having “gaps” that are the right “size” for the visible light to pass through.


We can make transparent versions of (some) metals, for instance aluminum oxynitride, we just don’t because the process is very expensive and difficult for little benefit.