With a few materials and a little time, it is possible to build your own projection screen television up to 100 inches. Here we will take any size television or computer screen and turn it into a 100 inch projection screen television.
Measure the height and width of the actual screen of your television or computer monitor. Be sure that you do NOT measure the the box area that surrounds the screen.
Mark out the measurements on the cardboard or wood with a pencil. The depth should be 18 inches. You should have four pieces. The diagram below shows the measurements of the four pieces.
Cut the cardboard or wood with a Stanley knife or box cutter. Sit these pieces to the side for now. You will put them together later.
Cut out the focusing board. The measurements for this is the screen height by the screen length.
Take the pencil and draw diagonal lines from corner to corner on the focusing board. This will leave an 'X' on the board.
Place the fresnel lens in the middle of the focusing board and use the fifth largest circle on it to trace a circle in board.
Cut out the circle on the focusing board. If you are using cardboard, make sure to cut in a slight angle. This is to make sure that the front side of the hole is slightly smaller than the back.
Repeat steps 2 and 3 to make a another box that will fit inside the first box. The depth on this one should only be 9 inches. Also, since this will have to fit inside the other box, make your height and width just a tad bit smaller. Take off just a small fraction of the height and width of the actual screen size.
Paint all of the cardboard or wood pieces. The insides need to be painted black for a better picture . You can either paint the outsides black, leave them as they are, or painted another color. Only use flat or matt black paint for the insides. The blacker the paint, the better the picture will show.
Set all pieces aside and let dry. They need to be completely dry before assembly.
After the pieces have dried, use duct tape to stick the sides of the boxes together. Construct both of the boxes.
Reinforce the sides by running a piece of duct tape along the edges of the box to make sure that they are completely closed.
Insert the fresnel lens into the hole on the focusing board.
Attach the focusing board to the smaller box.
With your television upside down, attach the outside box to it with duct tape. Make sure that it is completely sealed so that no light can escape.
Insert the smaller box inside the larger one. Now you are ready to use your projection screen television. When trying to focus, start by pushing the television close to the wall or screen and then closely coming back until you have your desired screen size. Use the smaller box, focusing box, to focus in on the picture.