Step 1: Get Materials
Keep in mind what you may plan to shoot pictures of, for it will be a good factor in deciding how big you want your box to be. Since were laying poster board in the box, I would recommend that you keep the boxes' dimensions within the width of the poster board. The two colors of poster board I would recommend getting are white and black, but of course its also good to experiment and I find that blue and red also make good backgrounds. But, use any colors you wish. The color of the poster board sets the "mood" for the picture i.e. black background would be for like sleek watches or high dollar items, where as white may be for something like a vase with flowers, or something "light" and "airy"
Step 2: Prep the Box
You only assemble the bottom of the box, leave the top of the box flaps open, but make sure the bottom is taped shut. Try to tape the flaps together very closely to avoid a lot of light to get through.
Now lay the box on its side and assuming your box is square the side that is now facing up is your new top. This is how the box will be oriented from now on, whenever you take photographs.
Make sure the open end is towards you and cut the top and bottom flaps off of the box, but make sure you leave the left and right flaps.
Now (I used a carpenters square but I assume most people don't have a 3 foot square laying around, basically all you need is a straight edge. Get your marker and trace straight lines parallel to all edges creating a square shape on each side of the box, left, right, top and bottom. Make sure to leave about 2 inches of space between your lines and the edge of the box. If you have a larger box, I would go with 3 or more inches. Use your judgment on this one. Now if it helps, keep using your straight edge (whatever you may have used) and use it to aid you in using the utility knife to cut the squares out of each side of the box. Be sure to leave the former bottom now currently the back of the box taped up. Don't cut the back of the box that you taped up.
The picture should clear any questions you may have up. Areas in gray are the sections of the box that are to be eliminated.
Step 3: Cut and Apply Light Diffusing Material to Box Windows
Get your measuring tape or w/e you have and measure the square spaces in the sides of your box to get an idea of how big to cut your squares of material. Going past the edge is key here, in case you may not have realized that. So if your square space is 18 inches by 18 inches then you want your square piece of material to be 20 or 21 inches.
The look of the box isn't important, so going over the edge and doing a crappy tape job isn't the end of the world. You can still make it look neat if you tape the material on from the inside of the box. You could also glue it if that floats your boat. The 2 or more inches of space you left at the edges is where you will attach the light diffusing material to, whether you do it from the inside of the box or outside of the box. As you can see I just taped mine on the outside with duct tape. Look at the image notes.
The bottom of the box does not need covered with the light diffusing material, leave the hole..as a hole. The poster board will be covering the bottom anyway.
Note: Try to keep your material tight or "stretched" so to speak so its not all saggy or droopy in effort not to cause serious shadows or detectable light distortion....creases aren't a big deal as you can see my shower curtain has creases in it and I have found no effects in my photos.
Step 4: Buying Poster Board and Lights
The more gradual the curve of the backdrop, the less immediate gradient of shadow. It just takes some experimenting, but you will find that it works fine the first time you try it.
You can use lamps that you already have or buy new ones from Walmart or something.
Refer to the image notes for more information.
Step 5: Setting Up Lighting
I hope you enjoyed this instructable, it was my first one. Please let me know if you have any suggestions, or any questions that I may have left unclear.
Just email me millertime07MSU@gmail.com and include instructable or something along those lines in the subject so I can differentiate from spam and your emails.
Also, I only briefly proofread my sentences please let me know if something does not make sense or needs revised.