I have 30' of 8mm oplux I keep a figure 8 on a bite knotted in one end. I "single stick" up with a webbing 5 step etrier, and leave the oplux balled up in a pouch until I am ready to descend. When it's time to climb down I girth hitch the oplux around the tree, I attach paracord with a carabiner to my oplux and drop the tag end down so I can pull it free once on the ground. I then use a black diamond figure 8, but when you attach figure 8 pull a small loop of rope from behind through the larger loop and around the outside of the smaller part of the 8, keep the 8 so the small loop is at 3 o'clock, then rotate clockwise so the top of the 8 is at 9 o'clock and clip your carabiner(not the one on your tether) into the larger loop of the 8 and onto your bridge.
This should hold your progress and not let you descend. Once you confirm you are safely supported by the figure 8 you can remove your tether, lower any gear you dont intend to climb down. Then all you do is pull down on the small end of the figure 8 with your other hand on the tag end of the rope and you should be able to climb down. Anytime you let go of the figure 8 you should auto stop.
This method is cheap, once you do it properly it isnt hard and allows you to retrieve platform or stick at face level without worry, but plenty of folks will tell you it is dangerous so please, practice at low height and dont hold me responsible if you screw up.
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