For the first forms of indirect ceiling lighting neon tubes were still used, these were then due to their narrow shape and the same very strong luminosity ideal for this purpose. This was mainly due to the fact that the cladding made of wood or drywall made of plasterboard veneers have absorbed some of the luminosity and thus the light source had to bring enough luminosity.
In the meantime, interested hobbyists or do-it-yourselfers can use LED stucco moldings and light cove profiles instead of wood or plasterboard coverings, and instead of neon tubes today's modern LED technology takes the form used by LED Stripes or Flexbands . These are available in many different colors from warm white (2,700 Kelvin) to cold white (5,000 - 6,000 Kelvin) or alternatively with color change function (RGB) or a combination of both (RGB-WW or RGB-KW ) offered.
Another argument for the use of LED bulbs is, of course, the low power consumption and the associated lower heat development. Some possibilities and examples, how such an indirect lighting of the ceiling can look like, you can see on the following pictures or discover many more application examples in the BENDU Gallery.