Glass guys (and gals)

Where do glass repair guys get their glass from?

It's not like they're making it in the shop.

"Oh hello, Mrs. Hutchinson. Your front door you say. Now do you know the measurements? Okay. Okay. Well In think of our kiln guys start working on it now we can get it to you by weeks end. That's good? Very good. Goodbye."

No. That doesn't happen. 

So that means there must be a U-Line type catalog where glass guys go for their glass. They get on the phone, order the panels from somewhere else, then install them.

And if that catalog exists that must mean that somewhere, maybe multiple somewheres, there is a giant warehouse filled with glass panes and molten glass. 

Think about that the next time you go around neighborhoods breaking windows, you rascals.