Rapid protoyping

[Snowtractor]

It is possible, at this time, for those with a bit of dough, to take a part and have it placed in a three dimension stabilized scanner and have a detailed scan recorded . This scan can be used to send to a computer which controls a laser . This lazer , under computer control, lazes the surface of a heat activated polymer ( plastic ) to produce a pattern a layer at a time. There is a deck which lowers the hardened layer deeper into the polymer as each layer is built up at the surface. In a matter of minutes to hours a detailed hard 3 dimension model can be made complete with internal passages. This model can be used for casting or mold making , reference etc.
I mention this process here because it is a viable way to create a part that no longer exists . The more expensive the part is to machine, the more likely you would want to try to see if your draftings actually fit, before machining that block of metal. This process is becoming cheaper and cheaper, with small units being used in dentists offices to make teeth molds , and will become more common place in industries that is wasn't originally envisioned for.
I should add that certain types of non-destructive testing can also be used to make 3d plans of items too. Radar, xray,mri, catscan.
Interesting that advanced technologies will help restorers in the future , perhaps easier than now. Under bonnet heat sheilding being an example.
Sean