I must be doing something wrong here. I downloaded version 3.6 and unzipped as instructed, and sure enough, I've got the folder LIBFREDO6_Dir_36 and the file LibFredo6.rb in my \Plugins directory. But when I run Sketchup, nothing new shows up in the Window menu. Any ideas?

Thanks for the suggestion. Before seeing is I found another way, which is imperfect but so far it's seemed "good enough". What I've done is replaced a section of ramp with a Bezier curve, starting as a curve between a corner of the two sections I want to join (further apart than the little gap I showed). Once the curve is spanning the gap, I use a plugin called "FollowMeAndKeep" which copies the rectangular cross-section along the curve. It's not really following the path I wanted, but with care I can make it good enough for visual purposes, which is all I need right now. I'll check out your idea and see if that can do a better job. So thanks again.

I've been using Sketchup for just a week, trying to create a view of a complex model railroad layout. Things have mostly gone well, but I'm puzzled over one problem, which has come up multiple times. See the JPG view:
http://files.myopera.com/John98wbr/albums/661338/multi.jpg

This part of the drawing is basically a series of ramps at different levels and curvature. Sometimes I start drawing from the two ends, and then I have to make the ends meet up in the middle, as with the magenta ones in the picture. There's likely to be some misalignment, and I'd be willing to deal with it by saying "increase this radius and extend that part a little" or whatever minor tweaks are needed, but I don't see how to match the parts manually. Is there a procedure for doing it? I'd have thought that the problem would occur often enough that it's been solved various ways.

I just started Sketchup this week. I'm strictly a hobby user, though I'm an engineer and I could end up using Sketchup professionally once in a while, even if mechanical CAD really isn't my specialty. My main interest is in model railroads, and I found Sketchucation by searching on features of Sketchup that I thought I'd need. The plugins that people have posted are wonderful! One of the things that makes any Internet use so much fun is that just about anything you could ever want is out there waiting for you, free.

Maybe it's typical newbie behavior, but I couldn't resist starting with a challenge--a triple track helical ramp (yes this was a few hours of work for a beginner):
http://files.myopera.com/John98wbr/albums/661338/ramp.jpg