That is a nice and simple idea. I get that they are too small, but go with the idea. I'm sure that there are many workshops out there that could produce a bigger version just for your nephew. It's a long time ago now, but when I was at school doing metalwork (in the sixth form, so I was allowed in there without supervision), I used to make all sorts of stuff. I am certain that I could have made a set of those without much difficulty. In fact now I've thought about it, do any of the local senior schools still teach metalwork and could make a set for you? It would be a great project for some of the students to tackle, good press etc. Or maybe the local Technical College, anyone with a workshop. Going with this.... How about local engineering companies? The small ones may help out anyway, but I was thinking of the larger ones that might have an Apprentice Training School. The one I went to had incredibly well equipped workshops.
Contact the local newspaper, give some details and ask the readers if anyone can make a larger set. Nice human interest story.
Good luck!