I don't know if this will help anyone, or if it would be practical or not, but thought I'd post it on the off chance it does help.
I picked this up yesterday at Lowes. It is a battery powered LED Holiday Flashing necklace...little Christmas lights on it that are I'd guess 1/4" to 5/16" long each....there is a dime in the photo for size reference. Actual lighted length appears to be about 24" long, lights spaced about an inch apart. I picked up a couple for my kids, but can see where it might work great on some O or Standard Gauge cars.... or perhaps buildings. I know I've seen posts before asking about holiday lighting....so maybe this will work for someone. Cost was about $3.50 I think.