To fill a punching bag, there are several options available depending on the desired weight and resistance. Here are some common materials used to fill a punching bag:

• Clothes or scrap fabric: This is a good option for a lightweight punching bag that sways when hit. Cut up old clothes or other scrap fabric into squares and fill the bag from the bottom.

• Sand or sawdust: Adding sand or sawdust to the bag will increase its weight and resistance. Fill the bag halfway with old clothes, then pour sand into a plastic bag until its the size of a bag of sugar. Place the sandbag on top of the clothes and continue filling the bag with clothes until its full.

• Seed, grain, or rice: These materials can also be used to fill a punching bag, but they may not be as effective as sand or sawdust.

• Water or gel balls: These are good options for a soft filler that is easier on the joints. Bags with water or gel ball fillings are also popular for maintenance workouts.

Its important to prepare the filling materials properly beforehand to keep you and your punching bag safe. For example, if using clothes or scrap fabric, cut off any zips or buttons so they wont damage the bag. Additionally, some people prefer to make an inner lining out of plastic or foam before filling the bag to maintain its shape and balance.