As a time served apprentice with qualifications as a fitter I can advise to some extent.
What you are talking about is fitting a collection of parts together to make an assembly. That assembly will then need adjustments (the set up) in order to make the instrument perform correctly.
Any fitter will tell you that the job is never a case of fitting parts together. It is always a case of making parts fit. By your post, I can see that you are aware of this. It is the same whether sub assembly parts are made by hand or manufactured using CAD and CAM (commonly known as CNC). Tolerances in current manufacture may be tighter but there will always be a need for some skill during assembly to make the little modifications to individual parts in order for them to fit well together.
That said, many have gone before you and have been surprised by the results they can achieve.
I accept that you may not be as dextrous as you like but it is not always a handicap.
I'd have liked to help but it's a little too far to visit.
My advice is to use the tremendous resource that is Basschat. Take photos, post, ask questions, ask for local help. All of those things are freely available to you along with the vast resource that is the Internet itself. I am optimistic for you.