Forms On Fire - Forms On Fire provides a complete, customizable mobile forms and workflow system that is reliable and secure, works offline or online.
FreeCAD - An open-source parametric 3D modeler
ProntoForms - ProntoForms is a mobile business solutions application, converting paper forms onto any tablet or mobile device.
SketchUp - 3D for Everyone
Safety Culture - SafetyCulture is the operational heartbeat of working teams around the world. Its mobile-first operations platform leverages the power of human observation to identify issues and opportunities for businesses to improve everyday.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.