Plastic Sky Glass? Help?

I NEED SOME HELP PLEASE! I LIVE IN SAN ANTONIO AND IT IS HARD TO FIND PLASTIC SKY GLASS, THIS IS A GLASS THAT IS ON YOUR CIELING TO LOOK UP OUT AT THE SKY. WELL SINCE NO ONE CARRIES IT DOES ANY ONE HAVE ANY GOOD REMEDIES AS TO HOW TO CLEAN IT? MAY I REMIND YOU IT HAS SUN DAMAGE! SOMEONE PLEASE HELP!!