To make this block for a block and tackle, I used Evergreen .25" (6.3mm) Square Tube, 1/8" (3.2mm) Diameter Tube, 1/16" (1.5875mm) Dia. rod, .020" sheet styrene and 26 gauge floral wire.
Cut a .19" (4.8mm) length of square tube. Drill a 1/16 dia. hole in the center of 2 opposing sides. Drill a hole in the top of the square tube for the floral wire. Cut the .020" sheet into a square .1875" x .1875", drill a 1/16" hole in the center. Glue square in the middle of the square tube.
Cut 2 pieces of 1/8" dia. tubing .08" (2mm) long. Slide the 1/16" dia. rod through the hole in square tube, add a 1/8" tube, slide through middle styrene, add a 1/8" tube and slide the rod through the other side of the square tube.
Note: For a little more realism and clearance, use a small round file and make a groove around the circumference of the 2 pieces of 1/8" dia. tubing .08" (2mm) long.
Sand the assembled parts to an oval shape. Twist the floral wire into an eye and glue in the top.
There you go, a quick and easy block and tackle. The same technique can be done for different size Evergreen stock for different scales.