In message , Andrew Gabriel
writes
Secondly, what is the the best way of fixing them? Can you screw into the
upvc or is some sort of sticky stuff a better idea (but maybe not sticky
pads as you wouldnt want to absorb too much vibration). What about sticking
the wires to the frames too?

You can screw into pvc. I would drill a tiny pilot hole first, smaller
than the screw diameter obviously.

Isn't the upvc hollow? Is it thick enough to gain an adequate hold?

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dave @ stejonda