Hi Scott,

Not sure exactly what your question is.  Slide blocks run in the mortice 
in the wooden assembly.  Posts with screws ride in the slide blocks. 
The pencil bar is fixed in the posts.

There's a brief write-up here with more pictures.
http://billwebber.galootcentral.com/projects_in_progress.html

HTH,

Bill W.
Nottingham, PA
Woodworkers visit me at http://billwebber.galootcentral.com/