so a year later, i reckon i'll update this a little...
back in the fall, i was working with our laser etcher in the shop & got to thinking... we use this to friggin burn into stainless steel - surely i can cut some plastic. so i took my backing plate off the gauges & cut the twistlock holes into circles. fits right over them now at whatever position they happen to be turned in
and, as expected, those incandescent purple bulbs burned through their color in a matter of weeks :/ i just left them in there anyway with a orangish-purpley color going on. then, this week, i finally got my new bulbs in... i found some great purple LEDs last fall & have had 1 pair (as a test) that's been in all sorta different places to see where all it'd work as well as the build quality, etc. i finally bought enough for all the bulbs i wanted to convert over & got them installed in the gauges & ash tray this weekend (as well as a bunch in the car). holy crap, they're so much more amazing now!! these gauges look so much better than i imagine when i first came up with this concept. as you can tell, i'm pleased with the outcome! the purple's a nice rich color & the red show up even better now.