Bandages are generally made from used/old bed sheets. A good source for these sheets is from local motels.
Sheets with stains and or small holes are ok to use. Using flat or fitted sheets are fine. Sheets should be freshly washed. On each side, snip the edge and tear down to ‘square’ the sheet. Next, tear sheet into 2″-3″ wide strips by marking off first, then snipping the edge and tearing down the sheet. Before rolling, each strip should be between 4-6 yards (arm lengths) long. Usually, two stripes sewn together are long enough.