This demo is taken from an SBGrid webinar presented on November 11, 2011

RCrane: Semi-automated RNA model building within Coot
Abstract: RNA crystallography frequently results in electron density maps that are imprecise and difficult to interpret. RCrane is a Coot plugin that aids in RNA model building into maps of low and intermediate resolution. This plugin helps the crystallographer in placing base and phosphate atoms, and the plugin then builds the remainder of the backbone automatically and accurately.

Jump ahead to 10:36 to go directly to the demo itself and skip the explanation of how RCrane predicts backbone structure.