Buy your green screen material, which is typically available in film and photography stores and even some school and office stores. This material can be a flat board, paper or cloth. However, green cloth is a practical investment as it makes the backdrop more portable and not prone to paper's wear and tear.
Cut your green fabric to your intended size. As a general guide, make at least a 12 foot by 12 foot green screen backdrop to accommodate shooting a medium or long shot of a person. If you use a smaller backdrop, it can only accommodate medium shots and close-ups of people. The larger the backdrop, the more elements you can place in the scene.
If you intend to make a 12 foot by 12 foot backdrop, allot an allowance of at least 1 foot for each side as you would need the extra parts of the fabric for the green screen frame attachment.
Build a frame for your green fabric by buying PVC pipes from the hardware store. Although you can actually staple the fabric on a wall, this may not be very secured and it will result to faster wear and tear of your fabric, especially if you frequently transport your green screen backdrop from one place to another.
Put holes onto one side of the fabric at about every foot, then match each hole with your PVC piping. Drill the matching holes on the PVC pipes, then loop the material to the pipe using loop bungee cords or heavy-duty rubber bands.
Follow the same steps on putting holes onto the fabric and the PVC piping for the opposite side of the green screen fabric to complete your portable green screen backdrop.
Make sure that the opposite holes on the two sides of the frame match so as not to create folds on the green screen background when used.