...
Heat Set Inserts and Material Details
SPIROL Design Guide (Definitely read this!): https://www.spirol.com/library/main_catalogs/SPIROL-Inserts-for-Plastics-us.pdf
https://www.pemnet.com/bulletins_A4/sidata_A4.pdf
...
https://dental-media.formlabs.com/datasheets/Standard-DataSheet.pdf
Example heat-set insert: https://www.mcmaster.com/94180A363/
M2.5 Inserts for Electrical Mounting: https://www.mcmaster.com/94180A323/
Tips
I forget which page I read this on, but there’s aIn the hackaday link, it mentions putting a metal bar over top of the insert once the soldering iron is pulled out to flatten the raised ring of plastic around the outside of the heat set insert when installing.
Installation Video
Follow this video for installing the heat set inserts into 3D printed plastic parts.
Do not use any force when installing it, just let the weight of the soldering iron push it in.
Also, be sure to use the soldering iron vertical rail jig in the bay with the special tip to install the heat set inserts (https://www.adafruit.com/product/4239), there is one in the bay - this will improve installation repeatability (it is not strictly necessary, ensures you are installing them vertically and square).
...
Another part to be aware of is compression limiters: https://www.spirol.com/library/main_catalogs/cmpl_us.pdf