7 will give you 12

Freeman Crutchfield & Bob Uniack discussing roundhouse construction, pg 181

Awhile back I wrote about Robert Schleicher's four storey factory that he built from 2 Superior Bakeries and 2 Weekly Heralds. Vince reminded me that in David Sutton's 1964 book, The Complete Book of Model Railroading, there's mention of a 12 stall roundhouse built from 7 Revell Operating Engine House kits by members of the Burbank, Encino, and South Tarzana (BEST) Model Railroading Club. The author notes that at the time of shooting, the roundhouse was not entirely finished and that it takes a bit of "imagineering" to construct a twelve-stall roundhouse from seven Revell engine house kits, but it was done in both authentic and interesting fashion. Is this the kitbash that uses the greatest number of Engine House / Superior Bakery / Weekly Herald kits? The search continues.