Tinkercad
Autodesk Tinkercad is a free online CAD tool for everyone, making it the best choice to learn CAD for the first time and bring experiments and ideas into life with 3D printers.
The Shape tools in TinkerCAD enable users to brush or erase complex shapes by varying the current radius, providing flexibility in design customization.
Step-by-step introductory lessons
Snappy Rings Project: