I have a vague one, but still something you could try to do. In simple terms, stacking. And by that I mean, do your sound design thing, take the same synth and slow it down with rassel. Do this multiple times with different slowdown settings and master it a bit with other stuff.
![](http://at-cdn-s03.audiotool.com/2022/05/28/documents/txbz77p9hzy/snapshot640x480-2bb22441a997409581649971d842fb3a-320.jpg)