Sand-blasting cabinets?

One thing that hasn't been brought up is the glass window. Left alone, it will get etched so bad that you won't be able to see through it. I have a smaller Harbor Freight model (bench model). It works good but isn't large enough for wheels. To help with the glass, I bought a box of plastic from Office Depot. Not sure what they are called but used to be used with overhead projectors. The plastic would lay on the machine and the teacher would write on the plastic. Anyhow, I tape 3 sheets of these plastic things across the inside of the glass. I can sandblast for 2-3 hours before they need changing. Much cheaper than buying glass. Plexiglass wouldn't hold up either...
C