Some trial fitting with the prototype showed that there’s no possible way to route the connections through the socket, no matter how much I wanted that to happen, so I rotated the body to align the LEDs with the socket pin slots:
The body now builds with the flat end down, so the overall finish should be better:
A test run shows why I really, really wanted cool white LEDs in the strips over the arm:
The LED mount doesn’t have quite enough room inside the end cap for the holder to tilt as I wanted; the two 10 mm LEDs can be about 10 mm lower and slightly closer to the shaft driving the needle, which is what this rapid prototyping stuff is all about. Scrapping the existing lamp socket and (120 VAC!) wiring seems the best way to make this more useful.
Early reports on the arm LEDs indicate a requirement for more light, so the next iteration of those mounts will put two strips side-by-side…