Tinkercad is a free, easy-to-use app for 3D design, electronics, and coding. It's used by teachers, kids, hobbyists, and designers to design and make anything.
SketchUp is an easy-to-use web-based program that will help you learn to create 3D models of houses, sheds, decks, home additions, woodworking projects even spaceships.
KiCad: A cross-platform, Open Source suite for electronics design automation that effectively manages schematic capture and PCB (printed circuit board) layout.
TopSpice is an integrated electronic circuit design system with multiple capabilities, including schematic capture front-end, mixed mode simulator, graphical representation, and library of over 35,000 device models.