The 3 1/2 set from 1936

In 1936 the 3 1/2 set was redesigned. Like all sets, it lost the one-year architectural panels of 1935. The large 12 inch base plates were added, and this enabled the set to build many new and spectacular large models. This set was sold unchanged from 1936 to 1942. In 1942 Erector production ceased for the duration of WWII.

I think the 3 1/2 set never sold well because when the war ended and Erector production resumed the 3 1/2 set was not produced for a few years. And sales of pre-war 3 1/2 sets are rare. I have seen only one on a dealers list before the age of ebay. And of the thousands of Erector sets sold on ebay over the past several years, less than a half dozen have been prewar 3 1/2 sets. I managed to get most of those.