Eumig (Austria) started their film camera production in 1932 with the C 1 for 9.5 mm film stock. The C1 was soon fllowed by the C2, also for the then popular 9.5mm format. The C3 was Eumig's first camera for the 8mm film format, using double-8 film stock. B.t.w., the "C" in the type number means Camera, just like as the "P"-series were film Projectors.
At least two versions of the C3 existed, the black version and the grey verion. It might well be that the black version dates from before WW2 whereas the grey version dates from the 1950s.