I’ve been studying techniques for canyoneering. (We’re going back to Utah in October for some more canyoneering.)
I am impressed by all the different ways canyoneers have developed to make a safe rappel on a single line and yet still retrieve the rope.
This is one technique using a regular size climbing rope and then a 6mm pull cord.
“The normal "climber" method of setting up a rappel is to thread the rope through the anchor and rappel on both strands. This is a simple, straightforward method, and works in a lot of cases.
Using a block, the canyoneer can rappel single strand on the rope, then pull using a lighter line, such as a 6mm pull cord. This saves weight and adds flexibility.”
Here’s a system to retrieve all of your anchor slings after you descend: