Here are some spacers that can be printed in TPU or PLA. TPU will provide a bit of dampening for your flight controller and is what I prefer for stack spacers. I use these spacers with small zip ties to create a lightweight and flexible stack. The "lower spacer" is handy when using an esc with fets near the mounting holes.
The lower spacer is designed to allow room for a receiver below your stack.
These parts are intended to be mounted with zip ties instead of screws.
The lower zip guard protects the zip ties and bottom of your quad. IT IS SIZED FOR THE VERY SMALL (<2mm) zip ties.
To see how these parts are used check out this youtube https://www.youtube.com/watch?v=XE1B-4F6nro