Its how the french navy (used/experimented with) to do uniforms.
You'd stand in a room, they'd scan you using structured light (I think, this was ~2000) then they'd extract the key measurements. However, instead of just in time tailoring, they had a bunch of trousers/shirts/tops/jackets in common sizes based on the population, rather than pattern type.
This allowed quick mix and match without manual measuring. It also allowed sub sizes to be used
Dug out an article, didn't read, but the picture is the device I recall.
https://www.techguide.com.au/news/gadgets-news/new-3d-body-s...
Yes, you had to be in nothing but underwear, which was funny because when my dad tried it, we were in the middle of a massive convention centre.
In the beginning it was all hand modeling. It helped a bit that I did finite element analysis professionally at that time which involved a lot of 3D modeling as well.
About 15 years ago there was a small hype where photographers offered the service of 3D printing small figurines of you and your loved ones. I found one that gave me the 3D data. It was just a point cloud and hard to process back then.
Around the same time I had to get an MRI and talked the technician to give the data. Again it was hard to work with back then, but I learned a lot about DICOM.
More recently I asked my dentist for the 3D scan data they are doing there and he was happy to give it to me. It's just my mouth and teeth, but it's excellent data that worked straight in Blender.
I also experimented with the LIDAR of my iPhone a lot. I use Polycam for that, but mostly for spaces and objects. About four years ago a colleague who makes masks for his LARPing asked me to help him with that, but the resolution is too low for a head and face. Depending on your aspirations it could be good enough for full body scans. Especially since Polycam can do photogrammetry now besides the LIDAR scans, but I have not used that enough to form an opinion yet.
Speaking of apps, there is also Face Cap which can export the data from iPhones front facing facial recognition hardware, including facial expression animations in 3D. This is the data that Memoji use in the background.
By far the biggest progress we had is in software in my opinion. Blender is fantastic for working with models of all sorts, including human body models. There are many free base models you could fit for your needs (the ones Blender Studio offers are excellent and free), and there is MPFB2 if you want a generator. Apart from Blender there is still MakeHuman which progressed a lot in the last decade.
When it comes to services there are a ton that offer photogrammetry, 3D scanning and motion capture.
We live in exciting times and it was never that easy to create a model of your body.
EDIT: Regarding existing services, this was also a hype about 15 years ago along with the figurine services. I believe in Munich, where I live a company that offered it was called xsuits, or similar. When I search for this I find a lot of dead services and companies. Seems to have been just a fad, which is sad, because I think it is a really good idea.
While searching I found youlittle.com which offers 3D full body scans and sell you the processed data and edited models in various forms. Maybe something like that is the easiest and most convenient route.
It's pretty good if you can get a decent coverage of photos. I did a scan the other day of a microphone holder and, apart from some thin gaps I couldn't get a good angle on, it came out well enough to see what was going on (it was warped).
With the rise in scraping, impersonation, identity falsification? Not even slightly interested in full body scan tech.
Driver's License? The crooks will probably have a much easier time than me going to the DMV.
Put you somewhere you weren't with video generators? Hey, they've got a hi-res, full-body naked file of you for reference on video addition and substitution.
Why does the IRS' think this account's more me than me? Much better at video substituting your fake face for ID.me than the nonsense of you trying to use the ID.me cell phone app.
Print your face out as a mask Mission Impossible style and use your identity during robberies. The list goes on and on.
And these people never seem to delete anything properly, no matter how much you check. Ex: See food kiosks that photograph every customer, for some reason, with no deletion. (was in a college or factory somewhere earlier)
https://mezzoforte-lounge.com/challenges/zozo-2bsuit-order-r...
There are many companies trying to do something here, both tailoring and virtual try-on, e.g. https://news.ycombinator.com/item?id=28354021