What are some alternatives?
When comparing PathEngine and Clara.io, you can also consider the following products
SelfCAD - SelfCAD is an online 3D modeling and slicing software.
Blender - Blender is the open source, cross platform suite of tools for 3D creation.
EQUINOX-3D - EQUINOX-3D offers 3D modeling, animation, photorealistic rendering, photorealistic VR content creation, CAD/CAM, 3D printing, laser-cutting and more.
Cinema 4D - Cinema 4D is a 3D modeling, animation, motion graphics and rendering application.
Aartform Curvy 3D - Aartform Curvy 3D is an easy and fast sculpting program for Windows.
MODO - Modo by Foundry brings you the next generation of 3D modeling, texturing and rendering tools in a powerful integrated software package.