There are several other objects that you can safely use as substitutes for paintballs to shoot from a paintball gun. You can go for these options if you have run out of paintballs or if you don’t want the mess that paintballs create while you practice. You can use hard rubber balls; they are not squishy but don’t hurt much; soft rubber balls are a much safer option. Water balls are also a great substitute. You cannot use anything that the gun can shoot, though, like marbles, plastic bullets, or spherical stones; these can be dangerous.