Sandbags were a big need for me; I didn't have any and I tend to shoot outside. Throw in an outdoor wedding an a week of moderate winds I was in a pinch. So a trip to the local rock distributor with a five-gallon bucket resulted in fifty cents worth of sand.
The bags were constructed from sleep pants that have built up to ridiculous levels in my drawers. So, tie the legs off at the bottom, really work the knot down. Fill the legs up with sand, cut with scissors and tie the top. Done. One 5-gallon bucket resulted in 5 sandbags and a tighter filled stabilizing bag for shooting.