Texture would be smooth. The shapes would be flat to rounded and would likely not be the same surface shape as the Empeg buttons.

The knob, at least for the D key Mk2a, could be done the same way. 1 piece of plastic to handle the key, the other piece could be a plastic cap or a metal cap. That way the knob could be end glow or side glow. While the Emepg knob could be matched, it would likely not be exact if done at all.

As to the glue, with a jig that would hold the pieces in alignment and acrylic or even super glue, I think it could work. I am concerned about bubbles but that may not be such an issue when they're clamped together.

I'll try some prototypes to test some of these guesses. I'll post back when I know more.