If you're looking for free or open-source alternatives for 3D modeling and plant design, there are several options available, though they might not offer the exact functionality of SmartPlant 3D. Some of these include:
SmartPlant 3D (now known as Intergraph Smart 3D) is a high-end enterprise engineering software that does not have a legal "free download" for the full version smartplant 3d 2018 best free download
: It excels in large-scale projects where multiple teams (piping, electrical, structural) need to work on the same 3D model simultaneously without overwriting data. If you're looking for free or open-source alternatives