Hi Seaspray
I have been putting some thought to the fibre optic . I thought I might flatten of the dome on the LED so the cut ends fit better to the LED then use shrink sleeve to hold the fibres together then use shrink sleeve to join them together.
In a former job I looked after sauna sang these had star effect in the black ceiling ,these were fibre opiptic made by Sovorski(maby not the right spelling).There light source shon through a revolving disk with a pattern in it making the lights twinkle . The fibres were all bunched together ,with each fiber having shrink sleeve on it then these were shrunk sleeved on to a short piece of acrylic rod and the hole lot covered in shrink sleeve ,then the light shone at the revolving disk , in this case the lamp was a 12volt dichroic bulb
David