I always keep a quantity of unfinished, discarded or 'dead' material which I attempt to resurrect from time to time. In this case, after considering and experimenting with various possibilities, I eventually combined two contrasting electronic sequences (drone and random noise), slowed them down by a quarter and added a touch of delay, etc.
More on the 703rd weekly Disquiet Junto project, That’s How You Got Killed Before — The Assignment: Revisit something that you just couldn’t get to work last time — at https://disquiet.com/0703/