Dick - We were in Wisconsin a couple of years ago and saw some of these lamps. While I am not normally into this type of artsy lighting these were truly spectacular - not only in design but in the lighting effects. Have you contacted the Taliesin preservation commission
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might be completely off base but I believe they had information concerning some of Wright's lamps and other furnishings in their bookstore. They might have also had some kits of some of his more simple items (not this lamp).
This might sound nuts but..... Have you considered gathering all of the photos and information your can find and scaling individual dimensions based on the overall dimensions provided in books and web pages -- and then laying it out yourself? I am an old, board draftsman and the process of laying out a scaled design is not that daunting. The tough part comes from figuring out the assembly methods and electrical components. I am sure these lamps use lighting and electrical parts that are outdated and even hazardous by today's standards.
I had this thought when I was looking at some of them in the museum bookstore. As nice as they are, they did not look horribly complicated in their assembly. You appear to be interested in Wright's designs. If you ever get to Wisconsin, I recommend a trip to Spring Green. Wright wasn't the only radical thinker of that age and in that area - but probably the best.
RonB