My friend JackBack had some broken neon style LED tubes laying around.
Made a quick light installation using this bracket connector.
printed with SLS so didn't care about FFF printability.
probably you need to cut a bit of them bottom like 1-2mm do have a flat surface.
Inner diameter is 26mm, scale it accordingly for other tubes.
Closes with a ziptie.
Covered tubes with cheap dichroic foil.
Use 3m for better effect.