A few years ago I bought a limited edition Downtown Deco kit that Randy made available on the Railwire:
https://www.therailwire.net/forum/index.php?topic=22073edit: I can't believe that was 4 years ago 
The kit has nicely detailed wall components, but the thick plaster makes for a fairly heavy assembly. For the diorama base itself, I decided to use a pine box-type construction, for something a little more substantial.
->photos to follow