Hello Bob
I wish you well in your search for someone who can help – I am afraid that I am not your man. What I think will make it difficult for you is this:-
Up until the 70's / 80's there was still a reasonably thriving engineering industry in this country. A small percentage of skilled craftsmen used their skills to further their hobby of model engineering. Back then someone like you would have had a far better chance of finding a bod to do your job.
Back to the present. With maybe a few exceptions, the only blokes that could engineer a job like this would be time served toolmakers. (I don't believe they make 'em these days do they?)
If you loosely accept the aforementioned then it follows that you would most likely be looking at a retired toolmaker or instrument maker or similar.
Such a man who is retired and pursuing what is often an expensive hobby is unlikely to need to work for a crust. I am a retired toolmaker and at 66 my hobby is a way of relaxation, keeping oneself occupied and keeping the old grey matter from atrophying. I expect that chaps around here of my age – or older – might well feel the same way.
Nevertheless, never say die and good luck in your search.
Rik
P.S. If you are successful and find your man (or woman) and can spare the time, please come back here and prove me wrong.