Smarter Every Day has a very interesting video[1] inside the factory of United Launch Alliance in which, among a lot of other things, shows the friction stir welding used in their Atlas Rocket[2]:

[1] https://youtu.be/o0fG_lnVhHw

[2] https://youtu.be/o0fG_lnVhHw?t=1933

This is a great video. Thank you for sharing it.

The gimmick that Eclipse Aircraft (Paul Allen) used to get almost half a billion in investment is they would use FSW instead of rivets.

But that wasn't the main problem with creating a new jet, which has a myriad of other issues before certification.