Here are some pics of the Uncle Milton "Star Wars" Force Trainer II set.
As you can see, it is quite large and makes for a decent diorama building. You will need to fabricate a full rear wall though as the rear is comprised of a simple support bar that runs along the bottom of the open section (although, I could always use the front piece from the second set to make a full back...).
Aside from the headband, there are no electronics in the set. The "hologram" effect is created by slipping a tablet/ipad under the top piece and running an app.
I left off the top piece as I plan on using it for a different project after dremelling off the "Star Wars" logo.
You can see that it scales pretty well to the 3.75" figures.
Not bad for $14.99 each.