FreeCAD - An open-source parametric 3D modeler
Time and Material Plus - Time and Material Plus is a software program designed to process billable data and deliver transparent billing results.
SketchUp - 3D for Everyone
Cleopatra Enterprise - Cleopatra Enterprise is an out-of-the-box cost estimating and cost management solution built by and for cost estimators and project controllers.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
eTakeoff - Construction projects work on a strict schedule and budget. eTakeoff offers the only construction cost estimation software that makes everything easier.