I've got an Einstar I bought on a Black Friday sale. I had been eyeing one for quite some time and watched several reviews. Making for Motorsport and SuperFastMatt on Youtube have both done some reviews and demos of different scanners over the years. The main thing that drew me to the Einstar was the software at the time. Not that I don't still have my frustrations with it, but everything I had heard was that even if it was annoying to deal with, it was still noticeably better than the alternatives. I think that gap has closed in recent years, but I've never used any other software myself to compare.
As far as whether I'd buy one again, that's tough. Some of it boils down more to the fact that I really just don't use it that often. It was a neat tool I was interested in getting and thought I would use more, but realistically it sits on a shelf more than not. I just haven't found as many use cases for it on the stuff I do, but I'm also just a hobbyist and not constantly trying to make or reverse engineer parts. The other issue I've found is more what you do after the scan. I can get some really neat looking stuff that seems like it would be super handy, but actually importing it into CAD to do any kind of modeling with or around is painful. The biggest issue I have is just the lack of easily defined axes. It makes it really hard to position a scan in a model in such a way as to build parts around it. And it's not really surfaces, more just points, so it's equally difficult to measure anything from a scan within CAD at least. There is some inspection software out there like GOM Inspect (now Zeiss inspect I believe) that will effectively average out surfaces to let you take measurements. I tried that once to see if I could pull suspension points from one of my cars.
So yeah, I think it really comes down to what you want to use it for. I have not had great luck scanning small objects with it, even with the "small" mode setting on the software. I still can't figure out what that setting even does. However, it does scan small detail fairly well, so a workaround could be to put a small object on a larger object with details that you can track easily. The other thing I've learned is more just how to use it. Instinct tells me to move it closer to scan more detail, but that's not really how it works. You need to move it over a surface at a consistent distance and sweep more than pivot. It gets tricky if you want to measure something that is behind something else because you need to maintain a minimum distance. This was most noticeable when trying to scan my suspension. I think it would do great if I had an open wheeled car that didn't have a fender in the way, but when I had the limitation of only being able to hold the scanner as far away from the suspension as I could get before running into the fender, it made it a little more difficult. That said, it does scan well when you're working in its operating conditions. I think a lot of it just comes down to me learning how to use a scanner more than the scanner's fault. I think I probably had unrealistic expectations for how to use it.
I know that sounds like a lot of doom and gloom after reading over it, but in the end it was a more of a "would I buy a 3D scanner again period" vs "would I buy this one". The scanner itself is less of the equation to me than the software and post processing. The software has gotten updates over the years to add some new features like an undo button and some model manipulation that has made it better. To me though it's still the difference between something like Blender and SolidWorks. Both make "3D models", but they are very different at the core of how those models are made. I compare Blender to something more like a 3D photograph. It looks like a thing and has depth, but it's not solid like a CAD model that you can manipulate and cut and measure and stuff. There is software that will convert the two, but it's more expensive than the scanner itself. I think I have some pictures of scans I've taken around here though. I'll see if I can find and post some.
