I finished trimming both front and back channels of the annunciator. Also trimmed off some additional material on each end to leave the tabs where the unit will mount to the panel. (The idea is that I will run two long screws through the instrument panel, one at each end of the annunciator. These screws will then go through the tabs on the front channel, then through about 5/8" of empty space between the tabs, then through the tabs on the back channel, and it'll all be held together with two Nyloc nuts.)
Sandwiched between the two channels, of course, will be a thin Lexan sheet with the light legends printed on them.
The dividers are held in place with a tight fit, and also with dabs of E6000 clear adhesive. (The second photo below shows them held with blobs of "hot glue," but this didn't work out as well. The E6000 is much more robust.)
Additional material was removed on ends of both pieces. This leaves tabs for mounting them.
Radio Shack sells some nice LED holders (Cat #276-079) that fit in 1/4" holes.
Back side of the LED holders. They just snap right in.
