I built a set of Speakerlab Model K speakers back in the early 70's and used them for years. I was going through my old files and found my copy of their complete construction plans for their version of the Klipschorn. I have scanned them into my computer and would be willing to email them to interested builders. Their instructions say 3 sheets of wood per cabinet, but I was on a student budget and cut a pair out of four sheets. My cut diagrams are included.
Garthforschools@gmail.com
There are sheets on a couple more of their models, an Electrovoice folded horn and what they call the university classic.
They also had a paper on crossover design which I have not scanned yet, but may be of interest to someone.