Thanks Much, for the replies!
I may have erred in a few areas.
I used foil and a toothpick but maybe I should have been a little heavier on the hardener.
Also I tie in an unheated loft and when I leave for the night, so does most of the heat.
I will take all of your suggestions and try again. I think I can strip the flies down to the copper bodies and build up the thorax again. This time I may try the Loon products or the 5 min epoxy.
In any case I will mix like a chemist and try a few samples first.
Cheers All!

"These fish we are catching have a disorder...Their heads are too close
to their tails."
~Jimmy Houston~