LeoCad
LeoCad
Website: http://www.leocad.org
LeoCAD is a CAD program that uses bricks similar to those found in many toys (Just like Legos). Currently it has a library of more than 1000 different pieces.
I downloaded and ran this program, the learning curve is a little steep, but there is an excellent tutorial on the website that should get you building all kinds of creations before you know it.
Installation is very easy, all you need to do is go to the files page and download the latest version of LeoCAD to your computer, then double click it and follow the setup instructions.
Once you have LeoCAD installed take a look a the Online Tutorials to learn how to use it, or visit the LeoCAD Gallery to see a few creations from other users.
Elizabeth

