Most glowing costume jewels go one of two ways: a bought plastic bauble with a light tucked behind it, or an opaque print that hides the light source completely. This build takes a different route. The maker designed a faceted jewel from scratch in Blender using basic shapes, printed it in transparent PETG, and lit it from inside. The crown itself was not designed by the maker; the jewel was made to fit a black ornate tiara with curled horn-like bands and a central circular mounting frame, as a glowing touch for a vampire princess costume in black and red.
The assembly is tidy. Two 3mm LEDs light the gem, powered by a 1632 battery in a custom compartment. There are 1mm holes under the battery compartment, and the LEDs' negative sides fit into them. Everything is pressure fit and snaps tightly together, and the lit gem snaps into the tiara's central socket, where it sits well. The walls are about 2mm thick, and the print was done completely solid with no sparse infill.
The jewel was printed at full speed, and the maker is happy with the diffused light; at night it looks great and is really bright. The glow reads as a flickering, flame-like red and yellow. This print served as a fit test, and the maker likes the diffuse look and is only curious about clarity.
That clarity is the open question. Slowing the speed and turning the fans off produced a giant mess, and the maker found little information online about printing PETG transparently. The next step is drying: a food dehydrator is set to be reused for drying filament, and a cheap single filament dryer was arriving. Whether clearer crystals can come from settings alone, without resin, is still unanswered.