How to Make a Plexiglass Display box?

by Janice
(Kansas City MO)

I saw several jewelers at an art show that had their smaller, more expensive items displayed in plexiglass cases. The artist said they made them. Just find a plastic company that sells cut-to-order, and go to a jewelery supply for the metal brackets that join the corners and sides. Well, I have had NO luck finding the metal brackets. Any suggestions where to look? I am not even sure what to CALL them when searching the internet.

Thanks!