Added the Queen Post truss type SketchUp output:

I don't know yet. What is a bona fide extension?
I'm thinking about taking the programming from my calculator that computes the truss geometry and re-coding that directly into the plugin. That way you can adjust the pitch, span, truss type, overhang and other parameters all within SketchUp itself. You won't get any of the actual engineering for the truss, at least not yet, but it will allow one to generate the truss geometry independent of the calculator which will make it much easier to use.
To do this though will take some programming hours which are hard to come by at the moment since my local customers are putting the food on the table. I tried to do some crowd funding for my calculator last year but that did not go anywhere. Maybe there would be more support for a SketchUp plugin?
Today I had someone from one of the SketchUp boards ask me to implement the output for the king post truss so even though it does not do the engineering for this truss type you can now get both AutoCAD and SketchUp geometry for a King Post Truss:

I've recently added the ability in my online truss calculator to output SketchUp 3D geometry. The generated file uses the plugin method (.rb) where you simply drop the file into your SketchUp plugins folder. The plugin prompts the user for the number of trusses to draw and the truss spacing so that one can create the usual array of trusses for architectural models. For example 4 fink trusses @ 24" o/c would give you something like this:

or a single truss might be:

The truss calculator has been around for almost two years but this is the first time I considered providing an output for SketchUp. I'm not a Ruby programmer (perl is my thing) but I found the SketchUp API to be very easy to use and the Ruby programming fairly straight forward and less clunky than even Perl.
Currently only the "fink" truss has the SketchUp output, the truss calculator is located here:
Technically this tool is geared toward the engineer but with the addition of the SketchUp output/functionality it might also be of some use for the DIYer who wants to draw up his/her own design in SketchUp.
Also note that there is a daily limit on the calculator since the server was getting hammered earlier this year and bandwidth became an issue.