I've been using CAD software for 20 plus years ... still a newbie really though, as I don't do it for a living.
You can at the moment print nylon, carbon fiber nylon, ABS, polycarbonate etc. for high temp products. Nylon prints at around 480 degree F and can easily live in an environment north of 300 F, ABS will handle 250+ F . Most of the filaments I use print at min 360 degrees F so their actual melting points are pretty high .. but degradation and creep will take place at lower temps.
Many filaments are available with carbon fill, copper fill, iron fill which does make them conductive .... so now you have cursed me with another project ... trying to electroplate something made of conductive filament ... which of course leads to chrome plated plastic.
Some filaments can be smoothed with an acetone vapor process ... basically suspend the item above a bath of acetone ... timing can be critical as the part surface can run if left too long. And most of the plastics will sand reasonably well. Most of the parts I'm posting photos of are printed in "draft" quality, not in the slower, higher definition modes ... which still isn't "smooth" but it's better than what I'm showing ... downside is it takes quite a bit longer.
I've looked into laser scanners ... problem is that a decent one is still about $5k. The Amazon variety for a few hundred appear to be very limited in usefulness other than for scanning the general shape. There are also high end probe type scanners that physically probe a part to generate the file ... but they have obvious limitations for cavities and hard to reach areas. Basically, if you have the money, it can be done and done very accurately .... a LOT of money. And yes this is often used for scanning in entire autobodies etc.
A lot of the CAD software I use is .... well, "obtained" and "cracked" by processes I'm not proud of. Spent a LOT of years on the internet, been around computers a long time, the stuff can be had, but considerable precautions must be taken if you don't want to end up with your PC under the control of someone in the former Soviet bloc or the software manufacturer disabling the software remotely. Back in the day the major CAD software companies kind of left open back doors to their software because they realized that in order to sell software that cost thousands they needed a user base, young people that could go into school already being familiar with a product ... who would encourage universities to buy hundreds of licenses for said software ... kind of like cigarette companies getting kids started early
But .... the good news is, there is very good stuff out there for free now, both the open source CAD/CAM software and things like Autodesk Fusion 360, probably the most widely used CAD/CAM software in the world .... and it's free. Autodesk gives it away, it does have some limitations but is perfectly usable for the hobbyist. And .. SolidWorks, the dominate CAD/CAM/Engineering software in the world ... you can get a student version (fully capable) for a subscription of $100 a year ... which I will be getting before long. Right now I use .. we'll call it "bootleg" versions of AutoCad, Autodesk Inventor, 3DS Max etc. for design work ... then import into legit Fusion 360 for CAM work. Which is why I want to change to the student version of SolidWorks ... can do all the design and CAM work in the same program.