[MrFlippant]

Most of the consumer/prosumer stuff I've seen uses some kind of light projection, either patterns or lasers, or just regular bright lights, pointed at the thing you're scanning. The thing is placed on a platform of some kind with a known dimension, often with registration marks or patterns of its own. That platform then rotates a small number of degrees between scans. This is repeated up to hundreds of times, to get every angle of the model. How the data is stored and interpreted is proprietary to whatever gadget is being sold, but some of them use open source photogrammetry.

My point is that the object, such as a slot car body, doesn't actually need to be set onto the platform as if it were sitting on all four wheels. One could create a frame, and suspend the chassis from the frame by whatever means necessary to hold it firmly in place "in the air" so that the scanning process gets both the outside (top) and inside (bottom) of the body. Yes, the results will have the frame and poles or string or whatever is holding the body up in the air (in my mind, vertically, as if it were a rocket ship on a launch pad), but that could easily be edited out in whatever 3d modeling program, such as the oft referenced Meshmixer.

The quality of the resultant model will depend entirely on the stability of the model being scanned, and the accuracy of the scanning system.

Whether you get a high quality model out of an expensive machine, or a low quality model out of a consumer system, there WILL be work to be done to get it to a point where someone can print it and be happy with the results.

When the day comes that what people believe is possible matches what is actually possible, and for a reasonable amount of money, I will rejoice along with the rest of you.