Measure the wall onto which you wish to hang your projector screen. Once you have the measurements, cut the bed sheet down the the desired size, leaving 6 inches at the top and the bottom.
Cut two pieces of PVC piping -- one for the bottom of the screen and one for the top -- using a hacksaw. These lengths of piping should measure around an inch longer than the full length of the screen.
Stitch the piping into the bed sheet. Roll the top of the sheet over the pipe until it is completely covered and use a sewing machine to sew a seam into the fabric that holds the pipe in place. Alternatively you could hand stitch it using a needle and thread. Repeat this process at the bottom of the sheet with the other piece of piping.
Glue the ends of the sheet to the pipe at the top and the bottom using the glue gun. The glue will prevent the sheet from sliding off the pipe.
Drill two holes into the top pipe. These holes should be at either end of the pipe, through both sides, and wide enough to fit a piece of string.
Thread the string through the holes in the top pipe and tie knots to secure them into place.
Attach two hooks to the ceiling, spaced apart so the string can be tied around them to hold the screen in place.
Roll up the screen when you are not using it, and store it away.