3. The scanned model may need engineering to fit your real railway bits such as wheels, bearing, etc.
4. Is the scanned file suitable to take into a 3D drawing package and to than manipulate?
Simon
This is my first post and whilst wandering through past posts I found this one [and the two previous ones from Osgood] upon which I feel I have something to contribute.
It is entirely possible that events and inventions have overtaken me but as far as I know, only two 3D packages allow the importation of *.stl files such that they may be edited meaningfully. By that I don't mean cleaned up/holes filled/meshes repaired etc., suitable for 3D printing - I mean fully reverse-engineered.
The packages are "Space Claim" which has a limited ability to take an *.stl file and turn it into a fully featured and editable parametric 3D model and 3D System's "Design X" [formerly "Rapidform XOR"] which is designed specifically for that purpose and exports parametric versions of *.stl files in Parasolid, Catia, Inventor and Solidworks native formats. Essentially it acts as a manual [or alternatively, semi-automatic] three dimensional version of what "Corel Trace" does for 2D bitmaps. Alternatively, think of it as the equivalent of a 3D optical character recognition package dealing with lines and freeform surfaces rather than dots.
So the answer to Question 4 above is yes - but the Design X software package costs around £18k and requires a fair amount of experience to use.
There are a number of agencies such as Europac [in Crewe] and Central Scanning [in Bromsgrove] who will do this work - both the scanning and the reverse engineering - and they can also 3D print the finished article in whatever scale and material [including a complete burn out wax] you might need. Their work is excellent but costs are high [a 1/24 truck cab reduced to 1/43 (or 1/76 enlarged to 1/50 etc.,) will cost about £900 less VAT] - Hardly surprising when you consider the costs of the software, scanning equipment and the labour intensiveness of the reverse engineering process.
Additionally there could be copyright issues when dealing with masters that are not the intellectual property of the person wanting [modified or otherwise] copies.
I don't see this situation changing in the near future as it is very much a seller's market at present. For purposes not wholly related to model railways, I do actually possess an ultra high resolution scanner and the Design X software so can claim to have some idea of what I'm talking about.