more progress:
This is aluminum, probably do a brushed finish with satin clear on top to keep fingerprints off. The two end pieces were tricky, there is a lot of curves going on there. The ends will be more or less permanent behind the headliner future me will figure out. The center piece will be removable without disturbing headliner.
I'd like to incorporate two small gimble mounted reading lights, like in a airplane or RV, but haven't spotted ones I like yet, most options are about 4", I want 2" or less. So far the best option seems to be those little 1" penny clearance lights with clear lens.