I admire the beautiful work done by @clyde.
Usually most “plastic” light switch covers are made out of bakelite, which is one of the oldest synthetic resin invented, which is non-conductive and heat resistant.
I googled bakelite MSDS and found:
" 10. Stability and Reactivity
Stability: Stable under ordinary conditions of use and storage.
Hazardous Decomposition Products: May produce carbon monoxide, carbon dioxide, nitrogen oxides and hydrogen chloride when heated to decomposition."
The key word being “May”. Hydrogen chloride is a gas form of hydrochloric acid.
Short story, do not laser bakelite.