I came across these nymphs. They are NOT epoxy or UV resin or any kind of resin coating like Sally Hansen.
So my question is how are these nymphs made? Answer will follow in after you have had time to think about it.
Foam with clear shrink tubing?
These nymphs are ceramic. I don’t know the exact construction method but I think is similar to what I describe below.
They are lead wire wrapped over the hook, covered with layer of ceramic paint that is fired in a kiln between each step, then covered with a clear glaze that is fired.
They’re cool but being ceramic they’d have to be kiln dried right??? That would affect the temper of the hook. I can see doing them with the colored stretch cord then as NJTrout said clear shrink tubing. Would definately be softer.
Never would have guessed ceramic!
It’s a water-based paint that sets at room temp overnight and is then thermo hardened in an oven @ 300-325 degrees for 30-40 minutes. I don’t imagine that’s warm enough to disturb the hook temper.
Thought this category was ‘Fly Tying’, NOT ‘Fly Molding or Baking’. Why not just use a Rappala or Hula Popper and be done with it. Sheesh!
Calm down…all will be OK…
We could have a combination fly swap/cookie swap and only have to heat the oven once!
Some of y’all get bent out of shape way too quickly!
Here is another link. I was wrong about the need for the nymphs to be fired in a kiln, Copy the link below into google translate
http://www.jpdessaigne.com/Lesnymphes/nympheombre/nympheombre.htm
Cast and Hit a rock…clink, shatter?
Please remember to get the cookies out of the oven before the polymers go in. Otherwise they might end up as dangerous as Swamp Witch Betty’s apples. 
Ed