Big Clive, who describes his channel as the trashiest electronics on YouTube, has mucked around before with making his own LED lamps. Now he has monkeyed with 3D design and printing for the first time to create a simple adapter that turns a test tube into an LED bulb.
As he points out, this is a decorative, ambient lamp, not proper room lighting.
The circuitry is a simple classic capacitive dropper and I ended up managing to fit in about 26 RGB slow colour changing straw-hat style LEDs. Note that it’s better to use the slow change RGB LEDs instead of the fast flashing ones as there will be a high open circuit voltage across a flashing LED while it’s not lit and that might damage it. You could also use standard LEDs for continuous illumination. The light only uses about 1W of power, so it’s more for decorative use than room lighting.
This was also Clive’s entrance into the world of openSCAD. He includes the openSCAD script he created which you can cut, paste, and tweak to your own purposes.