Ok chaps, pretty much all done.
Tips I've found out on he way:
Pilot drill the holes to full depth properly - 1mm drill is good
Hand held pcb drill will drill slightly oversize. Using a pin chuck might have more control
Push rod into hole, hold sharp blade along neck and rotate rod to score all round almost flush to neck. This gives a cleaner break with less waste, so less filing later. The picture attached is before I tried this!
I used the insulation tape to pull the rod out of the hole, added a spot of superglue to the end and re-inserted. Easy, but have some kitchen roll handy to wick off any excess - less finishing later.
Drill hole in insulating tape to put over rod for initial filiing flush, I used 600grit paper to go flush then buffed with a nail buffing board to finish
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All in all I'm pretty pleased with how it turned out. They are plenty bright when first charged.
It's pretty hard to take meaningful pictures in operation:
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