Some jewelry, some plant pots, a lot of gaming stuff. I use a 3d CAD software called OnShape. Autodesk is kind if the standard, but I run Linux and OnShaoe is web based.
Here are a few things I've designed
Magic deck box:


This is not quite the finished product. Added a notch and groove to make it more secure
Dice Tower:

Mario pipe pot designed specifically for carnivorous plants:

Some nerdy earrings shaped like the outlines of a standard set of RPG dice:
