The Premier Society for the Premier Line. A thriving group who cater for anyone interested in the LNWR and thus a source of information on LNWR wagons and just about everything else too.
The only book written so far about LNWR wagons. This volume covers open wagons, cattle wagons, timber, glass and furniture wagons, plus sections about Earlestown Works, where most of them were built and the standard design features. At this link you will also find an older book which covers some LNWR wagons in the LMS era.
These people buy and sell steam models. They often have Gauge 3 in stock. If not, then look at their archive pictures for inspiration, or their list of LBSC designs for ideas.