Not yet, it hasn't arrived ;-)
Thank you for all the responses.
I was intrigued by the blowtorch- especially as the bits in question are about 10mm long (or will be when cut)- If the idea works, they will be tiny 'light pipes' over some (small) LEDs on a PCB so they can be seen when the PCB is in a box- removing the LEDs to move them isn't impossible but the PCB isn't the best quality and I'm not convinced the tracks/pads will survive. (I planned on a clear box originally - the PCB was assembled a long time ago- but the one I had in mind is no longer available.)