Loris,
24V LED's:
No 24V LED's available - if you consider that an LED is in fact a diode, then you can understand why the chances of ever having a 24V Diode are pretty near impossible.
The first diodes were Germanium, in the 1950's and had a Vf (Forward Voltage) drop of about 0.3-0.5V. Silicon diodes, developed later, were more stable, with much less leakage, but had higher Vf's - about 0.7 - 1.2V. The higher the Vf, the hotter the diode, and correspondingly the greater the waste of electricity.
Today with the push to run everything on batteries, and make the devices last longer while running on batteries, technology has pushed the average Vf on Silicon diodes down to 0.4-0.8V, exactly the opposite of what you'd like to see on a LED with a Vf of 24V. That imaginary 24V LED would be a toaster with the heat generated!
So, I think that we're going to see LED's drop their Vf even further down from the current Vf's of 1.8V-3.3V, to less than 1V in the future.
Glueing the leads:
I sprayed the inside of the black housing with silicon spray to make it slippery. I then put the LED's leads in and filled the cavity with hot-glue. That way, the hot-glue dries solid into the form of a block, but I can easily remove it if I need to, without resorting to invasive or destructive methods.
Menahem
Learn from the mistakes of others - you'll not live long enough to make them all yourself!