More like what did I do to a washer today.
Finally figured out how to insert the rivnuts into my roof for the roof rack extension forward. You see online really expensive tools for setting them which seems like a real ripoff and without actually using it you don't know if it will really work or not. After some internet and Youtube research I finally figured out the system which works which is really simple and costs about $2. I will need 6 M6 rivnuts but I bought 25 to be covered, and I've already used about 5 playing around.
It consists of a 6 mm bolt, a couple washers, a 3/8" coupling nut, a 3/8" wrench and your impact gun with a socket the same size as the bolt head. And a larger washer that is the same ID as the rivnut so you can practise. The washer will function as the hole in your roof until you can figure out how to to it right.
The coupling nut is too long so cut it in half then clean up the edges. Drill out the inside threads so the 6 mm bolt slides through. Assemble all the pieces as shown in the photo with the 3/8" closed wrench around the coupling nut so it doesn't fall off.
Hand tighten the rivnut on the bottom and "insert" it into the large washer (your roof).
Hold the wrench and tighten with your 10 mm impact socket. The rivnut will squish down and compress onto the washer (your roof).
The issue here is you can see how far to tighten when it's around the washer but you can't see how far to tighten when it's in your roof and you'll want to be careful to not overtighten with the impact driver. But you can remove the assembly from the rivnut once it tightens up and look inside to see how far it comes up, then tighten some more if you need to.
Also some were off centre until I figured out how do do it cleanly (basically, with properly sized washers that don't shift to one side).
Off centre:
Centered!
Hopefully all 6 come out this nice in my roof!!