Depending on what you’re trying to do, you can get EL panels and EL tape which can be cut to custom size & shape, and the part connected to the wire will still work (even with holes punched through it).

It’s also possible to make EL paint and coat surfaces with it, though definitely and involved process and not cheap. Lumilor sells EL paint kits which were used in this youtube video to coat various surfaces. This article from Hackaday specifically mentions painting 3D printer objects, but I didn’t see any examples.