LibreCAD is a free, opensource alternative to the popular 2D and 3D modeling and design tool, AutoCAD.
AutoCAD is a multi-purpose program that's fantastic for making precise 2D and 3D buildings, models and more in the industry standard CAD design. Unfortunately, it's also quite expensive, which might make it difficult for students or other people on a budget to purchase.
That's where LibreCAD comes in. A free, opensource tool that lets you create and edit 2D models, LibreCAD is a legitimate alternative to the more expensive AutoCAD. Support and documentation on how to use the program is also available user-made and available for free on the developer's website.
LibreCAD provides users with a palette and a variety of retouching tools that will let you both create and edit 2D designs. For more hands-on users, LibreCAD's availability as an opensource program allows you to customize it to your liking without any cost except for time on your part.
Beginning users might find it a little difficult to use initially, but the extensive tutorials made by other users and developers definitely goes a long way in helping you learn the program's ropes. The only real downside to the tool is that there's no support for 3D model creation, which might limit its usefulness, depending your own needs for a CAD-based application.
As a no-cost alternative to the far more expensive AutoCAD, LibreCAD can't be beat for creating and editing 2D designs.
LibreCAD supports the following formats
Open / Save: DXF, CXF
Export: BMP, JPG, PNG, PPM, TIF, XBM, XPM