Backdrops and Walls

I have this idea in my head that a good 28mm skirmish game should be playable on something as small as a 12x24 inch board.  Along those lines I've created half a dozen 12x12 terrain boards that I can position together in a variety of ways.  

At that scale however, it always feels like the action could or should spill out further.  In an effort to 'contain the game' I've been toying with backdrops and walls that can be added/removed as the occasion dictates.

Here's some shots of the same, presently I'm up to Prototype #2 with #3 in progress 👌

The rough-and-ready Prototype #1

Two 12x12 boards using prototype #2 - those are some
28mm scale figures in for reference

A somewhat closer shot

How the backdrop/wall holds together - Prototype #3 will likely employ 6 inch walls on what's appearing as the bare cardboard on the bottom of the current Prototype #2.