A couple of questions:
-Could a 3D scan be made of the incorrect pilot (or any part for that matter), and then be modified to be correct using software? It seems that the answer would be yes, but would that be the best way to do it?
-Are there 3D print and scan shops that might have really high quality printing and scanning equipment that you could use to help create your file and then send the file back for printing once you have it ready?
I'll try to answer these questions as best I can. The caveat applies that I know Autocad pretty well, I have some experience with 3d printing, but have never directly utilized 3d scans with a 3d modeling software.
A 3d scan could be made of most any part you desire to copy. Big or small. You could 3d scan a prototype locomotive. Or a room and it's contents. Or something like a 1/48 loco pilot. And the model pilot should be as simple as finding a shop that has a 3d scanner.
The results of the scan - often known as a point cloud - can then be imported into any number of programs. The latest version of Autocad supports point clouds. I would presume that SolidWorks and Inventor (the Autodesk equivalent of SolidWorks) would also support this technology. From a quick reading, Autocad can interpret planes, edges, centerlines, and other obvious geometry found in the scan file. While the imported file is not specifically a .dwg file that can be readily edited in Autocad, it can sort of be traced to create entities in the drawing file that can be edited. It sounds like planar geometry would be simple to convert, while more organic shapes (think f7 nose) would require more effort to convert to drawing format.
Autodesk point cloud use in Autocad
Now whether this would be an effective way to create the 3d file for your specific pilot or any other part depends on several factors. But the simpler the part, the more effective it would be to just model it from scratch (presuming access and skills with an appropriate program). It all really depends on complexity of part and quality of data available to model from. Accurate, comprehensive dimensions make drawing even more complex objects pretty simple. The head-scratching over inconsistencies is what takes time and affects part quality and accuracy. The bottom line is that if you had the part you wanted to copy and modify readily available, I would probably prefer you just give me that to work with rather than the 3d scan.
Regarding 3d printing and scanning providers, the answer is again yes. At least for printing, and I suspect there are now plenty of shops that can scan things too.
The obvious big player for 3d printing for a lot of people is Shapeways. They have lots of media available, with lots of corresponding issues, costs, and results. But an alternative I have used several times is to search locally for 3d printers. A simple google search will yield results, or you can go to a site like 3D Hubs. You can find local "hubs" offering printing services based on your zip code. There are varying levels of print types and quality, materials, and costs. Some hubs are simply people like ourselves that have purchased a desktop printer like a Makerbot and are offering to print for others to lessen costs of ownership. Others are people or companies with higher end machines that again are trying to offset costs and employ their machines more efficiently.
I have never sought out a 3d scanning service, but I would expect that some of these hubs that function as businesses might also provide scanning services as part of a 3d model creation environment. They may also provide help in creating a new 3d model from scanned data. But my guess is that even if you can't find a printer that also provides scanning, you could get a lead on somebody that does do scanning.
Do some internet searching, and take a look around the Shapeways site or the 3d Hubs site. If you find a local printer you can often communicate directly with them to discuss your project and their capabilities.
And I think you should also take a look at the changes you want to make (especially coupler openings) and ask if it isn't something you could as easily accomplish with some styrene sheet and CA at a significantly reduced time and dollar cost. I absolutely enjoy creating 3d modeling in Autocad, and I love the "perfection" of producing things from that 3d model, but sometimes the process is more complicated than need be.
I hope this helps somewhat, and I'll be happy to answer any other questions as time and knowledge permits.
Jim
