My housemate and I were talking about this just this afternoon because
we've got an elder tree in the back garden... She said elderflower
champagne was best (though, like you say, it does take a while). We
located a decent looking recipe here:
http://www.channel4.com/food/recipes/chefs/hugh-fearnley-whittingstall/elderflower-champagne-recipe_p_1.html
It seems that swing top glass bottles are maybe the one, but just
about everything carries an explosion risk (see comments in link
above!) We've got a 1l glass swing top in the kitchen but will be on
the lookout for some more. We're thinking of maybe using some old
Grolsch bottles if we can find them.
I guess you could use the flowers to make a kind of syrup to add to
puddings or compotes?
Re: The system, I got this as an email...
Anyhow, let me know how you get on,
Ellen