This afternoon I began to put together the HTML for the timber truss GUI (what I have so far):

I think I've reduced a metal plated (bolts) timber truss down to twenty (20) parameters.
Hopefully the preview panel will help simplify the entry of these parameters and give the user instant feedback on what each one does. With these sort of trusses the look and feel of the truss is every bit as important as the structural aspect so a preview is very important.
The preview panel will not only show the timbers but also the metal plates and exact position of each bolt.
Once the user submits "go", the timber truss module will draw one (1) timber truss with all of the timbers, metal plates, bolts, nuts and washers.
In the global options the user will be able to specify the bolt standard and the washer standard as well as set the material (color) for the plate and hardware.
As usual the design and programming is a little more involved than I originally anticipated but in the end it should be quite dramatic to be able to create a fully bolted and plated timber truss.
I'm probably going to need a full week to complete this, so given my current schedule and hours it will probably be 2-3 weeks before this is ready to release.