Nice route. Always wanted a cnc...
Been having some rough times lately, but thought id offer a little more advice before its regrettable.
The bar hinge mounts you have are not as robust as the originals.. and I suspect they wont hold up too well for duration of use.
See if you can get someone to send closeups of the mounts.
Even the originals had their weak points. I had to rebuild my assembly. I was fortunate to find a hobby shop that sold the thin walled tubing that matched the original spec. I drilled the holes, and then injected some hot glued into the tubes ends to keep them still so they wouldnt bend/flex/loosen. .. and while hot, inserted the mounts in place.
The tube thickness is important. Too.thick... and there will be a drop off and or hop point... where one bar meets the next. You cant have a sticky spot on a game like this.. as it will throw off the much needed, and quite critical, gameplay control.
I ended up using brass, cause I thought it looked great... and was a better match for the look of a bar themed game. However, after considering it more after the fact... I was thinking that the original tube may have better durability and less friction, with long term use. I think I at least clear coat sprayed them lightly after polishing them.
I wondering if a 3 tube / bar system wouldnt be a better idea. A system to lock the main bar in center would be needed.
As for the surface and hole internals... you want these glass smooth. Any surface friction will ruin gameplay.. as the ball may get slowed or stuck. Dust often was the cause... and it was so badly effecting gameplay, that I had to take the entire machine apart, cleaning every surface... including the ball routing trails.
Probably want to use a laminate, and or a plexi covering. The holes will probably need plastic tube inserts... else the ball will wear them quite quickly... especially if using mdf. Plastic will also be easier to clean.
Dont merely rely on paint. Balls rolling over a painted and.or even a lightly clearcoated surface... will still tear it apart quickly. On pinballs, the longest lasting machines playfields have a clear mylar film glued on them.
Remember... mechanics are brutal. Friction, wear, mass, collisions... all a factor. Enough smahing... and things get loose. Loose parts cause misalignment. .. which causes grinding wear... which escalates quickly into permanent functionality problems.