FreeCAD - An open-source parametric 3D modeler
Flocknote - Flocknote helps super duper churches with their members.
SketchUp - 3D for Everyone
Rock RMS - Rock RMS is a community supported open-source Church Management System that provides innovative features to churches of all sizes.
LibreCAD - An open source 2D CAD application for Windows, Apple and Linux.
ChurchSuite - ChurchSuite is a cloud hosted, web-based church management system, ideal church database software for churches.