In late 2009, a tablet concept in development at Microsoft set tech blogs aflutter. The device was code-named “Courier,” and it consisted of two connected touchscreens that folded open like a book. The slate was seen as a fantastic product that could serve as a digital notebook on top of a standard media tablet, but Microsoft would later confirm that work on the Courier was being discontinued. A new iPad app was made available this week that resurrects the spirit of the Courier however, and it’s easy to see why: the team behind Paper by FiftyThree includes several people who once worked on the Courier project at Microsoft. Billed as the “place where ideas begin,” Paper by FiftyThree is a stunning sketchbook with a built-from-scratch user interface that makes recording ideas, notes, sketches and diagrams an experience rather than a chore. A video showcasing Paper by FiftyThree follows below, and the app is available immediately in Apple’s App Store for free.