If you're into tablet-style sketching, you're likely familiar with apps like FiftyThree's Paper or Adobe's Sketch and Line. Now, stylus maker Adonit has a sketching app that's designed to not only get the most out of its drawing accessories, but to boost your productivity as well. The software is called Forge, and its simple interface keeps tools handy, but out of the way so you can focus on the task at hand. When you need to create multiple versions of the same sketch -- a logo project, for example, -- the app allows you to easily copy the drawing and build on top of it, organizing the old and the new on separate layers. As a designer myself, that's been the most useful thing about Forge: the ability to try new things with the same idea quickly and easily, without mucking up the original.