Well, I have one "stage" (at least for the 1/6 scale crowd, though I've made 'partial' stages for some shots) -- that keeps getting re-dressed and re-used as story needs require.
Directions for making foam-core board room box -- this is the basic plan I used, though I made my stage a little deeper (and used an extra piece of foamcore board to do that). I also have pieces I slide in to raise the floor so the window appears lower (I use stacked DVDs in cases to hold the floor up... we're very high-tech around here!)
It was a group project; as you can see:
Early construction phase...
The first "story" was
Lady in Alabaster, so this is the construction of the artist studio that was the setting for the first two acts of the story...
Getting the window ready to be put up (it's clear plastic, in a wood frame, with the diamond pattern drawn in with sharpie markers. The plastic came from a Barbie outfit packaging.)
The stage as it appeared for
Lady in Alabaster. The plastic in the window actually was sometimes a problem, since I was using flash -- I had to angle my shots to avoid glare (not always successfully...).
The same stage 'redressed' with green-screen windows (really a different backboard) added. The green screen is flat paper (the pane pattern is printed on the green paper backing), which makes it a lot easier to shoot and then substitute in whatever outside scenery I want to show.
Another variation.... Same green-screen windows, but with image showing where the green was.
Tchat's room, another variation. It's all a matter of wall hangings (fabric) and different layouts, furnishings and props to create different places in the same basic set.
Ayame's room, another variation.
Backstage dressing room (movable walls re-arranged with new set pieces)
Akio's apartment.