KeepNote is a note taking app developed by Matt Rasmussen that you can use on different platforms including Windows, Mac and Linux. With this application, you can prepare to-do lists, set up paper outlines and make journal entries. However, there’s a lot more you can do with this free application.
FreeCAD is a cross platform parametric modeler that lets you create professional looking 3D objects. While the program has a lot of powerful features, no prior 3D or CAD experience is required. Not only is it easy enough for the hobbyist, but it’s got enough power for experienced CAD users who need advanced features.