If you are going the layering route, then you need to glue two pieces together until you have three parts.
I chose to have more length, but the pieces can be taped together for a taller box. Put together two ends at a 90 degree angle and put two pieces of tape towards the ends on the inside and outside. Do the same to attach the last piece to the other two. (also ignore that you can see my tape...it works!!)
...I needed a light box for my light box...
This black part is the backside, and with proper tape, I could have dark pictures with one part lit up, but doesn't help when you are trying to get clear pictures!!
This shape allows it to free stand and is easy to fold up and put away!
Set up the box and put the white paper as the bottom. Now you just need to position your light source. The sides and back will give a nice shadows and if your light is tall enough, positioning it from the top will just give the object.
The white of the walls and bottom still reflect the light well so the subject is still well lit. However, if you leave the camera on automatic you will need to do some editing to the final pictures since the camera will read the white walls and make the picture darker with this type of light box. If on manual see what the suggestions your camera gives are and either open up one f/stop or decrease the shutter speed one time.
And an example of putting my light box to work (with small adjustments since I did not do them on the camera):
