In preparations for #why2025 i made a @hswaw logo in the form of pseudo-neon made out of acrylic/PMMA, HDF, and an addressable RGBW led strip. 
like an onion, it has many layers, all 3mm thick
- full transparent acrylic on the front
- mostly full HDF, with frosted acrylic inserts for diffusing the led strip into the shape of the logo
- four structural HDF layers with a single continuous path for the led strip, which is slightly different (somewhat simplified) from the "front" shape
- backing PMMA layer, to somewhat protect the led strip, and prevent it from falling out if it unglues itself.
The general shape is based off of a version of the logo @q3k designed for the Warsaw Hackerspace website, aptly named "neon-syrenka.svg" ("neon-mermaid.svg"), but it took a few years before a physical representation in a (pseudo-)neon form was created 
most of the "artistic" design i did, including the simplified ledstrip path, was done in Inkscape, with the electronics box designed using FreeCAD
Warsaw Hackerspace logo depicted as a bright LED-strip pretending to be a neon, hanging in front of a cabinet and a safe box, with other lights turned off. The LED strip is colorful and addressable, and different segments are fading between semi-random colors.