Hello all,
You can indeed use netfab basic (free) to reslice the part, but I think with my model, it will give you a lot to think about.
I found it already difficult enough to make the parts fit on 20x20, so 15x15 would even be more difficult.
I can 3D scan (simply with skanect software and an xbox360 kinect sensor), but this is only usable for "organic" things, like people or animals etc. Not for trains or other stuff, it's not accurat enough for that. The dda40x is modelled in solidworks. If you want a 3D printer, make sure you have some 3D modelling experience, or you would always depend on others' designs ...
But don't be affraid of learning 3D modelling. AutoDesk (inventor) & Dassault (Solidworks) offer free trial versions. Autodesk even offers educational versions (in the broadest sentence of the word, so also valid for anyone eager to learn this stuff) for free, a valid legal 3 years license !
Don't bother with things like thinkercad etc ... They are to limited and are only good for real simpel stuff. Go directly for the "full monthy" ...
Also, there are more then enough good free tutorials on the web for this software.
I started using solidworks with a "step-by-step" guide, 13 parts, a few hundered pages.
I did part 1 till 4, spread over 2 evenings, I laid aside this tutorial, and started modelling in Solidworks

I started small, with some housing for Arduino & Raspberry Pi, designed a few Christmas ornaments, made a hexapod etc ... If i need to know more info about a specific feature in the software, that I don't know about (yet), I look on youtube with specific search-words, and I always find a video tutorial about my specific questions, so if I can, I'm sure you can do it also
I wil put all stl files on thingiverse (for free ofcourse), when my loco is completely finished.
(I hope to get it finished in Q1 of 2016, but due to my ongoing health-issues, I can't promis anything) Sometimes I can work for days, other moments just an hour a day or so, and sometimes I don't even touch anything for days/weeks ... It all depends ... But one thing is for sure, one day it will be ready
