Nonequal interval contours

Hi, I want to create nonequal interval (user-defined) contours for a DEM in ArcGIS. For example, instead of every 10 meters, I want some user-defined interval contours. Is it possible? I naively thought it might be possible, since the manual classification allows the user to arbitrarily define class intervals. The question is how to transform the manual classification results into contours. Any advice is highly anticipated.

Cheers.

Bin