Tabby wrote:
IIRC Rapid electronics has a range of button cell holders

Coin cell, but not button cell. This is the only button cell holder they
do:
http://www.rapidonline.com/Electrica...kw/button+cell

and that needs a PCB land area to match it, which I don't have. I could
make one out of copperclad, I suppose (I don't have etching facilities).
Thickness and weight of the PCB might be an issue too. (Anyone sell very
thin copperclad?)

Theo