As of April 30th, 2018, Autodesk Sketchbook has become free for desktop, mobile and tablet devices both Android and iOS. It is a raster-based drawing app that has 190 customizable brushes. It comes with a predictive stroke assistance feature that helps you draw straight linesand geometrical shapes, as well as apply the right amount to smoothing to curved lines.The user interface is quite intuitive thanks to the Rapid UI feature. By swiping your thumb on the screen you can quickly access brush, color and layers panels, which are hidden to give you more working space. You can always switch this feature off to have all the panels visible on the screen.On a mobile version, you are able to create a custom-sized canvas and export your artwork with a transparent background or save it as a PSD. However, all exported work will be only at 72 DPI. And if you remember, at Printful, we recommend the final artwork to be submitted at a minimum of 150 DPI resolution. As an alternative try using bigger file dimensions. If you have a file that is 24×32″ and 72 DPI, you’ll get a 12×16″ file with 144 DPI when you import it to our Printful mockup generator. Keep in mind that Sketchbook only supports creating your work in the RGB color space. All in all, this is a great app for creating your designs from scratch.