Working with Magnaflux Corporation, a company founded by his MIT MS advisor Alfred V. de Forest, Ellis starting marketing a brittle coating for non-destructive stress analysis under the name Stresscoat in 1941. After some time working with Magnaflux Corporation, he established his own consulting business as Ellis Associates. He was much sought after for consulting on new stress analysis tools, including the Stresscoat brittle coating he invented and bondedelectric resistancestrain gages invented at MIT during his time at the university. Measurements Group, Inc. bought Ellis Associates and continued to build many products Ellis invented and designed. In 1941 Ellis was an early member of the Society for Experimental Stress Analysis, now the Society for Experimental Mechanics. He was the inaugural recipient of the Society for Experimental Mechanics Lazan Award in 1968. He was named a Honorary Member of the Society in 1984, a position held until his death in 1997.