The Blue Print tool and the associated Building Blocks window.
The Blueprint tool lets you copy the shape of specific ideal loops to your protein. The Blueprint tool is available in certain design puzzles, and is described in more detail in the ideal loops article.
In the original Foldit interface, the Blueprint tool is available on the Actions menu.
In the selection interface, the Blueprint tool is available on the Main Menu, which can be displayed using the lowercase "p" keyboard shortcut.
The Blueprint tool has two floating windows. The Blueprint window displays the primary structure and secondary structure of the protein. The Building Blocks window displays ideal shapes which can be dragged to the Blueprint window and dropped on the protein at a specific position.
The Blueprint window also has buttons which access the Auto Structures and Idealize SS tools.
The Blueprint window also has an "ABEGO Colors" checkbox. If this option is checked, the primary structure of the protein is shown in ABEGO colors in the Blueprint window. ABEGO colors are associated with the Rama Map and are described in more detail in the ideal loops article.
If the "ABEGO colors" checkbox is unchecked, the primary sequence appears in "hydro" colors, where blue represents hydrophobics and orange represents hydrophilics.