Besides making awesome key chains, wave springs are very cool. It's easy to design your own. I did the tall one in Solidworks with the equation:
x = 1sin(t)
y = 1cos(t)
z = 0.125sin(3.5t)+0.075t
with
x(t) = radiussin(t) or radiuscos(t)
y(t) = radiuscos(t) or radiussin(t)
z(t) = amplitudesin(number wavest) + (if you want it to grow upwards) (spacingt)
The cross section is a rectangle.
I did the short one in Inventor with the Cylindrical equation:
r = 1
phi = t360
z = .25(sin (t360*5))
The cross section is a circle since Inventor is weak with controlling your sweeps. I guess at least that program lets me have a closed loop.
http://www.youtube.com/watch?v=zg1LRE0V7S4