While waiting for my 3D printer to arrive I have searched, read, downloaded, installed and tested (played with) so much that my head is ready to explode. One thing that is obvious is that there isn't much O scale available online that is ready-to-print (free or otherwise). I won't get into scaling here... because, it isn't always lineal and even that may be beyond someone's ability. Why should parts that are unavailable be continually modeled? Would it be helpful to *all* if we had a Repository for O scale 3D files to make it easier for everyone to find/upload/download these files?
I will make any of the 3D files I create freely available to all forum members (without having to do so privately) via ftp. I have quite a bit of storage/backup space (around 20TB) and 2 machines that run 24/7 as well as decent bandwidth... 200MB Up & Down.
Keep in mind that you can rescale any STL in your slicer to any size you want. I have taken HO models to standard gauge size. I use Ideamaker, you can also resize in different ratios for each axis (X, Y and Z). Just type in the new dimension. You can also slice the model into parts if it's too big to print, then just glue the parts back together. I have done GG1 shells that are 30" long (my printer will do 15")
I have purchased STL's from several modellers that have their stuff on Shapeways (who prints parts). Some of the designers will not even sell a copy of the STL because they are afraid that it will become 'wild' on the internet, available to anyone that wants to print it. They derive a small income everytime Shapeways prints a part.
I probably have 1000 hrs on my CR-1), and anxiously awaiting a large UV cure printer (very fine detail).