I was liberating some old hand tools from my grandfather's shop again, before grandma throws them in the garbage, and found some more interesting things. This cutting tool was one of them.
The following is a picture of the blade removed. The cutting edge when assembled faces inside the tool. The other is the underside of the tool.
Definitely designed to be hand held and has a blade with the cutting edge facing towards my hand in the picture. There is an adjustable guide that would allow cutting "stock" to 3 mm up to 18 mm.
My hunch is that you could trim veneer or cut of inlay stock by drawing the tool on a sheet edge but I am not sure. I can't go on anything but a hunch as there are no markings (that I can see) on the tool. It is possible that it is even not a wood working tool. My grandfather was also an electrician but this does not seem to fit for that profession. It was also in a wood working drawer and he was pretty organized.
What is this called, and more importantly what is it used for?