Scott-Atwater Manufacturing was the mother company who oversaw outboard production and also Scott-Atwater Foundry which was a separate entity. Cliff Scott oversaw the foundry for quite some time. The foundry produced many products such as Irons, ash trays, Manhole covers, and very large floor jacks that were used for heavy equipment. During the war effort The Scott-Atwater facilities were converted to produce Parts for Bombers and rifles and wide array of many items.
From the ad posted I was able to make out patent number 2259789 which shows that this item was invented by Cliff Atkins of Marquette company in Minneapolis Minnesota. It was applied for in 1940 and granted in 1941. There other patent numbers listed but were not legible in the ad. It is quite possible that this was made for the war effort and also sold commercially. Determining the other patent numbers could lead to more clues.