I finally got my lights and some time to work on this.
After you have installed all your lights go back and cover them with a thin coating of great stuff. I discovered this will give it a much nicer and more subtle effect when they are turned on.
Finish painting your foam. Let me give you a really important painting tip. As you can see from my finished effect photo, no one can see what color you paint the inside. As you can almost see, I wasted a LOT of time putting a nice paint job on mine. Just go ahead and paint the inside red or brown. Since I used orange rope lights I put a light coat of orange spray paint on the foam covering my lights so the color would be enhanced.
Next, slide the mirror piece into the bottom slot on your box. Then you can put your fourth wall on. Have fun with this step. It is not that easy. Be patient and if you can get help, do. I don't have pics of this step as I could not put the glass in, cuss, throw stuff, AND take pics all at the same time.
After your wall is screwed in place I suggest laying your box on it's side and taking an air compressor and blowing any junk out of it. Any trash inside can ruin the effect.
Add some Great stuff to the outside if you want. Then paint it when it is dry.
After you are done with that you can set your top mirror in place. It should just set right on top of the foam and corner supports as you can see in the pic above. I used a regular piece of mirror for the bottom. But for the top piece I used plexiglass with one way mirror tint installed. Given a choice, I would recommend plexiglass for both pieces for two reasons. 1) Glass or mirror is VERY heavy and 2) they are very breakable. The mirrored film works great.