I'm not sure how well known this guide is, but I remember showing it to Howland a year or two back and he had not seen it so maybe it's not that well known. Fairly great asset for learning to learn the toolset (pictures and all).
http://vnfiles.ign.com/nwvault.ign.com/fms/files/other/803/Toolset_Manual_V1.06.pdf
Just a browser format PDF, you can save it to your computer if you so please.
File no longer available here. If anyone knows someone who had maybe saved it so it an be rehosted please let me know.
Is this (http://neverwintervault.org/sites/neverwintervault.org/files/project/690/files/toolset_manual_v1.06.pdf) what you're after?
There are a few links to others here (//%22http://www.neverwinternights.info/builders.htm%22)
Enjoy.