Shape Memory Alloy Springs

I'm working on a project using shape memory alloy springs. The springs contract after running a current through for a while, and then they must cool down before they are manually stretched back to their original position.

This makes demos kind of short and kind of lame-- any suggestions for ways in which to improve this?

I've thought of adding more springs and rotating through them, running a lower current etc. These are somewhat helpful but I'm seeking other solutions...

What do you want to demonstrate?