On Wed, 11 Nov 2009 08:49:44 -0000, "N_Cook"
wrote:

wrote in message
.. My guess is that more domed means more change from ambient
temperature before it switches.

Dan

I will give it a go with large ballbearing in a cup and a press.

Another thing to try is local heating and quenching in order to change
the distribution of internal stresses in the dome.

--
Ned Simmons