A little

(been wanting to use that for a while!)
I've been experimenting with resins, namely epoxy glue like Araldite.
The first attempts were driven by necessity as I needed to fill something with glowing matter (more on that if it works?)
Still, point being that the first test was done using what I had on the shelf. Araldite. This was a standard form of the stuff but was translucent and a kind of yellowish colour (probably green or orange... But who knows?) This worked but was dull.
So I then purchased some clear epoxy for a mere 1.75 British pounds. Setting in 1min and curing in 5-30

Needed to be quick.
I've since found a curing in setting in 5min's and curing in 15... probably easier to work with?
Anywho, point being a 5ml syringe filled 3/4 full with equal line measures (well, pretty equal) of epoxy, hardener and glow powder. Will fill an approx 500mm length of acrylic tube with a 3mm bore

and glows like buggery!
much easier to cut and fit into the finished keyring and if you make different coloured rods up you can simply cut small lengths off by rolling a razor blade on them then snapping them off. Then insert as required.
For a multi coloured one like the one in Steve's post you just cut two short lengths that have the join meeting in the centre behind the cage so it's not really visible

Saves a huge amount of time filling fiddly little tubes and probably uses only 30%ish of the glow powder/tube due to the volume of the glue.

Finally a few pic's of the experiments...
The mix, prepared thus and mixed furiously using a scraper...

Using the scraper the syringe was filled and the piston re-inserted (pointing it nozzle up to expel the air.... you know? Like doctors do!)
(Note special syringe nozzle created for the filling of blind holes. Long thin and with a cross filed V over the nose... worked a treat

)

Syringe empty and the acrylic rod and a bit filled.

Turn the lights off.... And yes, that was wielded as a 500mm mini lightsabre


The original araldite tests next to the clear epoxy version.

And the lights off... The two longer ones were both blue glow. The smaller one was an attempt with the aqua version (this is always slightly brighter than blue) Here they look very similar brightness (all hit with a dose of 405nm (blue) "frickin laser beam" - Movie ref anyone?)

Hope that helps some of you?
You just need a few disposable 5ml syringes and some "clear" epoxy glue. (I had to turn the nozzle down to fit the acrylic tube)
Ralph.