I'm sitting here trying to figure out how to say NEVER rappel on paracord if there is any chance you will live otherwise. If you want small cord to try something like that buy some of the cord that is designed for it. DON'T USE PARACORD. Sure it has 550lb test strength, but think about how many cords go from your harness to your parachute when skydiving.... uhuh, it's not 2. The problem is that even entertaining this idea can lead to someone trying it and you don't have to fall far to break your back or anything else. Yes, they make devices for doing this, but NONE of them are designed for using with paracord. Sorry for how this is coming out but I can't stress strongly enough not to do this.

There are several kinds of stress put on a rope, you have static load (what paracord is rated for) and you have dynamic loads (you moving around while rappeling) and you have friction (rope going over edge, through decender) and you have the cumulative stress of the dynamic and static loads, every jostle and weight placed on it stresses the rope and those stresses are cumulative. Paracord can not handle these stresses.