First, I must say that you may be very disappointed if you do not have exactly the right bungee chord to do it.
I mostly use this in the bathtub, i loosen and restart stretching again often during a session.
It is composed of a bungee style elastic cord, thicker and stiffer than average, and a 2" ABS plastic pipe.
A pipe end is comfortable, there is a slot and a hole at the other end (like a keyhole) to put on and tighten the elastic cord.
The loop of the rope is tight enough to be able to put the glans across by pulling the tip, and tight enough to stay in when I pull hard on the rope.
I must undo the loop and soak the rope in alcohol from time to time to clean...
The trouble is that this exact model of rope is hard to find, and I can not remember the brand or where I have bought it.
I only remember that the hooks was in plastic and molded around the rope.
All the required qualities, thick, soft to the touch (I do not feel the elastic through the fabric) and steep (not too stretchy as many, many brands of thick bungee cords).
If someone knows or find THE brand to buy, let us know...
In this picture, the loop is VERY tight, I have stretched VERY strong the last time
I pull on the rope and I hung, as easy as it looks.
The cylinder is 2 " (5.1 cm) inside diameter by 12" (30.5 cm) long.