I bought and assembled an Anet A6 3d printer kit. With it, I printed various things, useful and pointless ones. Some of them were enhancements for the printer while others were needed to replace broken parts of the printer itself that was temporarily fixed using duct tape.
Apart from that, I also designed and printed a compact card wallet, a camera stand, 3d googles for smartphones and various other things. I designed these initially in Blender and later on on Fusion360.
This taught me a lot about CAD and slicing as well as design process from requirement to finished product.