GUI prototyping

[John Wells <jb@sourceillustrated.com>]

Guys,

Swing apps can involve quite a bit of detailed coding to produce a reasonably detailed prototype to a client. 

Are there any open or reasonably priced tools out there you use to make protoyping Swing apps a bit faster?  I've used NetBeans GUI designer, and while it's a step in the right direction, I'm looking for something more tailored to actual prototyping and not to the finished product.

Thanks as always for your input.

John