Back to the OP It's hard to tell from just a photo but the colour and the mention of how light it is makes me suspect it's MAZAK which is great for casting but an absolute nightmare to do any thing else with. It was much beloved by Uncle Joe Lucas Prince of Darkness. As mentioned it may be a promotional item but it has the look of a work shop retirement piece. Helped to make a few myself as an apprentice, slate mounts and machined etched brass faces for clocks, that kind of thing. Not really done nowadays but used to be common when we still had workshops where people served for many years.