I thought of a big problem with 100% metal buttons:
If you have a lighting kit installed, the metal button could easily short out the two LED leads on either side of the button shaft. Doesn't seem good.

The only alternative is using the plastic Farnell caps and creating aluminum button caps to fit on them. This should reduce the cost A LOT and decrease production time.

BUT, it's two pieces glued together, which I've never liked. Will they fall apart? What bonds metal to plastic, because that can't be easy.

Well, let me know what you think. I am finalizing CADs for this design and will have some price estimated fairly soon. I could even have them produced pretty quickly if they are as simple as I plan.

(I realized this about 3 weeks ago, when I last worked on the metal button project. I'll create the mock-ups of the lit options for metal buttons, in the next few days.)