Geroli,
What you need to do is make yourself up a trademark, just a simple little punch with some sort of symbol on it, then stamp it on some slightly hidden part, but easily found if looked for.
I do this with anything I produce for items that get exchanged for currency, I don't actually stamp it, but machine it into the parts themselves. Once it gets known what your mark is, if people recognise it as good quality, they will search it out.
I must have 100 or so pieces now, made over a long period of time, in various parts of the world. Maybe one day they will become recognised and collectable, or end up as recycled junk.
You never know, your family in the future could be sitting on a fortune in years to come.
John