Pencil is a drawing cum 2D animation software that’s free but offers features that you would normally find in expensive programs like Adobe Flash or Toon Boom Studio.
Pencil is designed to mimic the traditional drawing and animation process where animation artists draw individual frames and play them in sequence but at a very high speed.
Pencil also supports Onion Skins so you can reference the previous frame while sketching consecutive frames. Then there’s a camera layer for adding perspective to you animations.
Finally, drawings or 2D Animations created with Pencil can be exported to a variety of formats including SWF Flash, QuickTime MOV or a sequence of PNG image files.
Pencil is available for Windows, Mac and Linux platforms. It also works with your touch screen Tablet PC.