I have tried to explain several times over the years how the Rocket Engine Test Facility at NASA Lewis developed the electroplated-to-solid combustion chambers. Here is a YouTube video about the process: NASA's clever technique to make combustion chambers - YouTube
here is an overview of the RETF: https://www1.grc.nasa.gov/historic-facilities/rocket-engine-test-facility/origins-of-the-retf/
Here is the gang I worked with. The man on the far left with the Dutch boy haircut is George Repas, one of the main inventors of this process. I was still a technician at this time before I got my engineering degree. On the far right was Ed, our lead technician. We called our team Eddie and the Cruisers. https://www1.grc.nasa.gov/historic-facilities/rocket-engine-test-facility/retf-staff/