My brother had this idea book back in the 80s. We were both just blown away by how cool that forge was. The castle scene from this idea book was probably the most mentally stimulating LEGO picture I had seen until 2002 when I ended my dark age.
Sadly, Lego sets are not likely to ever come with the more simple assortments of parts that they had back in the 80s, so it would be nearly impossible for an idea book like this to ever be created again. Also sad is the fact that I missed the 1984 and 1985 castle sets, so I didn't have the parts to build the creations in this idea book. (Mostly the catapult wheels, and technic parts in general)
One interesting thing is that lots of the stuff in this idea book and from 1984 could be improved today by using brown or dark grey where appropriate, since both of those colors were not generally available for regular parts until about 10 years later.
Idea books were sometimes in stores, but very rarely. I believe my brother's book came from a large toy store like a Toys R Us, but maybe it just came from S@H. I don't really remember anymore, it's been so long.
This idea book almost makes me sad, because it reminds me of how truly great the 80s castle sets were, and it is unlikely that we will ever get a castle theme of that quality ever again.
By the way, a link to the article in this forum thread would be helpful.