Cut the 1-by-4 wooden boards to the desired lengths if necessary.
Mark an inward 45-degree angle on both ends of all four boards. Use a straightedge and miter box to make sure the mark is straight and accurate.
Cut all of the 45-degree angle marks with a miter saw.
Place the boards together so that the 8-foot boards are on the top and bottom and the 6-foot boards are on the sides, meeting flush at the 45-degree corners.
Place the metal "L" brackets at each corner, overlapping where the boards connect.
Pre-drill the holes for the screws by using the "L" bracket as a guide. Do this for all four corners.
Screw the "L" brackets in place to secure the wooden boards together. This is the finished frame.
Lay the blackcloth out face-down on a flat surface. Make sure there are no wrinkles in the cloth.
Lay the frame down on top of the fabric with the L brackets facing up.
Measure and mark the center of each side of the wooden frame.
Pull the fabric up over the frame and staple it to the top of the frame at the center mark of one of the smaller sides.
Pull the fabric tight and staple the fabric on the center mark of the other small side.
Staple the fabric in the center mark of one of the longer sides.
Pull the fabric tight and staple the fabric on the center mark of the other long side.
Alternate stapling to the right and left of the center staple on one side, making sure to pull the fabric tight. Staples should be about 3 inches apart. Staple all the way to the end of the board. Repeat this for the other three sides.