When I was working on the 1/96th scale Liberty Ship Model for the National World War II Museum Merchant Marine Exhibit, I needed to make a lot of pulleys in short order. I could have ordered pre-made brass pulleys, but for the number I needed it would have gotten expensive.
At 1/96th scale the pulleys were small. This technique can work for larger scales as well.
Materials needed are Evergreen or Plastruct I or H beam (depends on the width needed), tubing and thin styrene sheet. Make 3 discs, 2 large and 1 smaller with a hole in the center for the axle pin. Sandwich the small disc between the 2 larger discs on a pin for the axle and glue together.
Cut some of the web from the I, H beam to clear the wheel (discs) and keep some web, leaving the top and bottom flange. Drill a hole for the axle pin through the flanges of the beam. Sand a half round on the end of the web for a small piece of tubing. Glue the tubing to the web.