FidoCADJ - FidoCadJ is a free user-friendly vector graphic editor for Mac OS X, Linux, Windows and Android.
Figma - Team-based interface design, Figma lets you collaborate on designs in real time.
XCircuit - XCircuit: Home Page
Invision - Prototyping and collaboration for design teams
JumboCAD EDA - JumboCAD EDA contains 3 packages, Schematic Capture, PCB designer and Library Editor.
Sketch - Professional digital design for Mac.