you might look at some string and say, “that will never make my camera more stable!” but it can. and with a bit of tinkering and practice you’ll find that it can improve your chance of getting a shot in crummy lighting conditions compared to a hand held shot. the length of string you need will depend on how tall you are. hold the ball of string letting it out until it hits the floor, double it, then add 2-3 feet more. next tie two loops into the ends. put those loops on the bolt with a washer, add another washer then use a nut or wingnut to tighten it down. attach your camera.
to use it step on the string using both feet then pull up to make the camera more stable.