Russ, I apologize for my haste and should have simply removed the comments directed toward atka's condescending remarks rather than deleting everything. However, since they were only aimed at the video, they left a lot to be desired when it comes to what you're looking for.
Be that as it may, I have no idea how Mixy plans to let us create or add objects with smoother contours like the crane atka posted. He was right that I am not well-versed on the specifics of the process or exactly what tools will do the job, but I understand the basic process, and that and the high cost of Sketchup were my only points.
Anyway, AFAIK the steps are:
- create .obj (Wavefront) object files using a 3D editor like Sketchup. As I mentioned, the free version doesn't create .obj files, so you either have to buy the expensive Shop or Pro version or use another free or low-cost editor/converter that does. Windows Paint 3D creates .obj files, but I have no idea if they are compatible. Like I said, I'm not well-versed on 3D editing or .obj files.
- create a .lib file for the objects you created. I have no idea how to do this and atka didn't share much information on the subject. 
- copy or move the .lib file to the SCARM Lib folder. It will then appear in the Libraries menu for selection just like the track libraries (see photo). On my laptop, it's C:\Program Files (x86)\SCARM\Lib.
It looks like atka deleted his posts, including the video , but in the video, Sketchup appeared to create the .lib file and may have even put it in the Lib folder. It's sad that he chose to attack me rather than correct any errors I made or explain the process in further detail. The only real difference between SCARM and 3D editors is that the editors let you add diagonal lines on the 3D plane vs SCARM's 2D editing. Regardless of what Mixy decides to do, I hope he continues to allow us to add objects to the Lib folder. If I ever find out how to create the .lib file (for free), I may try my hand at 3D editing, something I haven't done yet.
I should add that one can create fairly complex objects in SCARM using figures. The problem is that while you could create your bridge with smooth diagonal beams laying on its side, you can't then stand it upright. 
