To make a perforated tin or zinc screen for a window frame 35 in. wide by 30in. high, cut from the metal sheet a rectangle 34 5/8in. by 29 5/8in. A tube frame round the edge makes a neat and strong finish. Now cut two lengths of 3/4-in. split brass tube 35in. long, and two lengths for the ends 30in. long; make the cuts at an angle of 45° so that the pieces of tube will mitre, and measure the lengths along the side of the tube opposite to the split seam. Place the tubes in position round the perforation, solder the corners strongly, and solder a semicircular-shaped piece of metal with a hole punched in it to the tube at the top corners, so that the screen may be hung on two brass hooks fixed at the sides of the window. Clean off the solder at the mitre joints, polish the tube, and enamel the perforated part green or other suitable colour, and the screen is finished.