Plexiglas would look cool, but...the reason it is metal covered is to contain sparks and flames. I have opened power supplies and circuit breaker boxes before and the only thing that contained the flames was the metal covering. Same reason construction codes require metal plates over junction boxes in residential wiring. Your uncovered, exposed Univolt is extremely hazardous.
-"You want to make it two inches - or, if you're working in centimeters, make sure it's enough centimeters for two inches."-Red Green