Over the last little while I've been developing an approachable 3D construction tool. My aim is to make a modelling tool that is really fun and easy to use. The above video demonstrates what I've come up with so far.
The software has a bunch of cool features, and the models you create in it can be exported for use in other tools that take 3D models, so you could 3D print them or use them in a game for example.
There's still a lot of work to go. The user interface is nowhere near final, there are many features that I would like to add (whilst maintaining the focus on simplicity), and I'm planning to shift development to focus on touch input, specifically iOS. That said, I'm very happy with the progress so far.